… .gitignore

Switches `require_git(false)` to `require_git(true)` in both the oxlint
and oxfmt walkers, and reverts the `parents(false)` workaround added in
oxc-project#17813 (oxlint only).

**Background:** `require_git(false)` was introduced in oxc-project#17375 so that
`.gitignore` rules would apply even in directories without a `.git` file.
A side-effect is that the `ignore` crate reads `.gitignore` files from
directories *above* the git root, which is non-standard git behaviour.
This caused a concrete bug: when linting inside a nested git repo
(`parent_repo/child_repo/`), the parent repo's `.gitignore` incorrectly
filtered files in the child repo.

**Why require_git(true) is the right fix:** The `ignore` crate's
`matched_ignore` already implements the correct git-boundary logic via a
`saw_git` flag. When iterating parent directories from innermost to
outermost, `saw_git` is set to `true` the moment the innermost `.git`
directory is encountered, preventing gitignore rules from any outer
repository from being applied. Setting `require_git(true)` activates this
standard behaviour.

**Why parents(false) can be reverted (oxlint):** `parents(false)` was a
workaround for the nested-repo bug. With `require_git(true)` the `saw_git`
mechanism handles this correctly, so `parents(true)` can be restored.
This also fixes the regression where running `oxlint src/` would fail to
pick up `.gitignore` rules from the repo root sitting above `src/`.

**Trade-off:** `.gitignore` rules no longer apply in directories that have
no `.git` ancestor. This reverts the behaviour added in oxc-project#17375.

…o boundaries

Switches `require_git(false)` to `require_git(true)` in the oxlint and
oxfmt walkers.

**The problem:** `require_git(false)` (introduced in oxc-project#17375) makes the
`ignore` crate read `.gitignore` files from directories *above* the git
root, which differs from standard git behaviour. This causes a concrete
bug in nested git repositories: `parent_repo/.gitignore` incorrectly
filters files inside `parent_repo/child_repo/`, which has its own `.git`.

**Why `require_git(true)` fixes it:** The `ignore` crate already
implements correct git-boundary logic via a `saw_git` flag in
`matched_ignore`. When iterating parent directories from innermost to
outermost, `saw_git` becomes `true` at the innermost `.git` boundary,
preventing gitignore rules from any outer repository from applying.
`require_git(true)` activates this standard git behaviour.

**Alternative discarded workarounds:** `parents(false)` was a workaround
idea for the nested-repo bug. That would cause a regression where
`oxlint src/` would not pick up `.gitignore` rules from the repo root
above `src/`.

**Trade-off:** `.gitignore` rules no longer apply when there is no `.git`
ancestor anywhere in the directory tree. This reverts the behaviour added
in oxc-project#17375.

Reverts oxc-project#17375

…s nested repos

Detects at runtime whether the walked paths are inside a git repository
and sets `require_git` accordingly — `true` inside a git repo (activating
correct git-boundary behaviour), `false` outside (preserving the behaviour
introduced in oxc-project#17375 where `.gitignore` rules apply even without a `.git`
ancestor).

**The problem:** `require_git(false)` (introduced in oxc-project#17375) makes the
`ignore` crate read `.gitignore` files from directories *above* the git
root, which differs from standard git behaviour. This causes a concrete
bug in nested git repositories: `parent_repo/.gitignore` incorrectly
filters files inside `parent_repo/child_repo/`, which has its own `.git`.

**Why `require_git(true)` fixes it:** The `ignore` crate already
implements correct git-boundary logic via a `saw_git` flag in
`matched_ignore`. When iterating parent directories from innermost to
outermost, `saw_git` becomes `true` at the innermost `.git` boundary,
preventing gitignore rules from any outer repository from applying.
`require_git(true)` activates this standard git behaviour.

**Trade-off:** None — the dynamic detection preserves oxc-project#17375 behaviour
for non-git directories while fixing the nested-repo bug for git repos.

…s nested repos

Detects at runtime whether the walked paths are inside a git repository
and sets `require_git` accordingly — `true` inside a git repo (activating
correct git-boundary behaviour), `false` outside (preserving the behaviour
introduced in oxc-project#17375 where `.gitignore` rules apply even without a `.git`
ancestor).

**The problem:** `require_git(false)` (introduced in oxc-project#17375) makes the
`ignore` crate read `.gitignore` files from directories *above* the git
root, which differs from standard git behaviour. This causes a concrete
bug in nested git repositories: `parent_repo/.gitignore` incorrectly
filters files inside `parent_repo/child_repo/`, which has its own `.git`.

**Why `require_git(true)` fixes it:** The `ignore` crate already
implements correct git-boundary logic via a `saw_git` flag in
`matched_ignore`. When iterating parent directories from innermost to
outermost, `saw_git` becomes `true` at the innermost `.git` boundary,
preventing gitignore rules from any outer repository from applying.
`require_git(true)` activates this standard git behaviour.

**Trade-off:** None — the dynamic detection preserves oxc-project#17375 behaviour
for non-git directories while fixing the nested-repo bug for git repos.

…s nested repos

Detects at runtime whether the walked paths are inside a git repository
and sets `require_git` accordingly — `true` inside a git repo (activating
correct git-boundary behaviour), `false` outside (preserving the behaviour
introduced in oxc-project#17375 where `.gitignore` rules apply even without a `.git`
ancestor).

**The problem:** `require_git(false)` (introduced in oxc-project#17375) makes the
`ignore` crate read `.gitignore` files from directories *above* the git
root, which differs from standard git behaviour. This causes a concrete
bug in nested git repositories: `parent_repo/.gitignore` incorrectly
filters files inside `parent_repo/child_repo/`, which has its own `.git`.

**Why `require_git(true)` fixes it:** The `ignore` crate already
implements correct git-boundary logic via a `saw_git` flag in
`matched_ignore`. When iterating parent directories from innermost to
outermost, `saw_git` becomes `true` at the innermost `.git` boundary,
preventing gitignore rules from any outer repository from applying.
`require_git(true)` activates this standard git behaviour.

**Trade-off:** None — the dynamic detection preserves oxc-project#17375 behaviour
for non-git directories while fixing the nested-repo bug for git repos.

…o boundaries

Switches `require_git(false)` to `require_git(true)` in the oxlint and
oxfmt walkers.

**The problem:** `require_git(false)` (introduced in oxc-project#17375) makes the
`ignore` crate read `.gitignore` files from directories *above* the git
root, which differs from standard git behaviour. This causes a concrete
bug in nested git repositories: `parent_repo/.gitignore` incorrectly
filters files inside `parent_repo/child_repo/`, which has its own `.git`.

**Why `require_git(true)` fixes it:** The `ignore` crate already
implements correct git-boundary logic via a `saw_git` flag in
`matched_ignore`. When iterating parent directories from innermost to
outermost, `saw_git` becomes `true` at the innermost `.git` boundary,
preventing gitignore rules from any outer repository from applying.
`require_git(true)` activates this standard git behaviour.

**Alternative discarded workarounds:** `parents(false)` was a workaround
idea for the nested-repo bug. That would cause a regression where
`oxlint src/` would not pick up `.gitignore` rules from the repo root
above `src/`.

**Trade-off:** `.gitignore` rules no longer apply when there is no `.git`
ancestor anywhere in the directory tree. This reverts the behaviour added
in oxc-project#17375.

Reverts oxc-project#17375

…o boundaries

Switches `require_git(false)` to `require_git(true)` in the oxlint and
oxfmt walkers.

**The problem:** `require_git(false)` (introduced in oxc-project#17375) makes the
`ignore` crate read `.gitignore` files from directories *above* the git
root, which differs from standard git behaviour. This causes a concrete
bug in nested git repositories: `parent_repo/.gitignore` incorrectly
filters files inside `parent_repo/child_repo/`, which has its own `.git`.

**Why `require_git(true)` fixes it:** The `ignore` crate already
implements correct git-boundary logic via a `saw_git` flag in
`matched_ignore`. When iterating parent directories from innermost to
outermost, `saw_git` becomes `true` at the innermost `.git` boundary,
preventing gitignore rules from any outer repository from applying.
`require_git(true)` activates this standard git behaviour.

**Alternative discarded workarounds:** `parents(false)` was a workaround
idea for the nested-repo bug. That would cause a regression where
`oxlint src/` would not pick up `.gitignore` rules from the repo root
above `src/`.

**Trade-off:** `.gitignore` rules no longer apply when there is no `.git`
ancestor anywhere in the directory tree. This reverts the behaviour added
in oxc-project#17375.

Reverts oxc-project#17375