Closes #8099

PR #7957 reorganized examples from flat
`apps/examples/src/examples/{name}` into category subdirectories
(`shapes/tools/`, `data/assets/`, `events/`, `ui/`, etc.). All ~115
"Related examples" GitHub links across 40 docs files now 404. This PR
updates every link to use the new paths.

Also fixes 2 misnamed example references in `default-shapes.mdx`:
- `custom-styles` → `shapes/tools/shape-with-custom-styles`
- `shape-options` → `configuration/configure-shape-util`

@steveruizok we sometimes point to hosted examples and sometimes to code
on github, not sure if intentional or not?

### Change type

- [x] `bugfix`

### Test plan

1. Open any docs page with "Related examples" links (e.g.
`/sdk-features/shapes`, `/sdk-features/tools`,
`/sdk-features/deep-links`)
2. Click the GitHub example links
3. Verify they resolve to the correct example directory on GitHub

### Release notes

- Fix ~115 broken GitHub example links across SDK documentation

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk: documentation-only changes that update URLs and a couple of
example name corrections, with no runtime or API impact.
> 
> **Overview**
> Fixes SDK docs and release notes that linked to example directories
that were moved in the examples reorg.
> 
> Updates "Related examples" links across many `sdk-features/*.mdx`
pages to point at the new categorized paths (e.g. `ui/`, `events/`,
`configuration/`, `editor-api/`, `shapes/tools/`, `data/assets/`,
`use-cases/`, `layout/`). Also corrects a couple of misnamed example
references in `default-shapes.mdx` and updates the v4.3.0 release note
link for the pin bindings example.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
de7a306. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

… 134 broken links (#8103)

In order to catch broken internal links before they ship (like the ones
fixed in #8102), this PR replaces the `linkinator`-based HTTP crawler
with a static checker that validates links against the content database.
The old checker required a running server, couldn't fail the build, and
missed most broken links. The new checker runs after
`refresh-everything` and before `next build`, failing early if any
broken links are found.

Along the way, this fixes all 134 broken internal links found across the
docs:
- 25 content files with stale `/docs/*` paths (should be
`/sdk-features/*`), wrong heading anchors, double-prefixed paths, and
renamed example links
- API doc generator skipping `TypeAlias`/`Interface` namespace members
(the `// TODO: document these` that caused `T.Validatable` etc. to
generate broken links)
- Namespace member path generation producing standalone paths like
`T-Validatable` instead of anchor links like `T#Validatable`

The checker uses a `--fail` flag to control behavior: `yarn check-links
--fail` (used in `build`) exits non-zero on broken links, while `yarn
check-links` (used in dev) only warns. This ensures broken links never
block the dev server from starting.

Additionally, this adds a standalone `yarn check-external-links` script
for manually checking external (HTTP/HTTPS) links across all docs
content. It deduplicates URLs, uses HEAD with GET fallback (30s timeout,
10 concurrent requests), and retries transient failures with backoff. A
skip list filters out domains that block automated requests (npmjs.com,
shadertoy.com). This replaces the external link checking that was
previously handled by linkinator but is too slow/flaky for the build
pipeline.

Also refactors the hardcoded Framer path prefixes into a shared
`fetchFramerPaths()` utility that fetches the live Framer sitemap. Both
the link checker and `app/sitemap.ts` now use this, so the list stays up
to date automatically.

Fixes a broken external link to the removed `custom-toolbar` example in
the v2.1.0 release notes.

### Change type

- [x] `improvement`

### Test plan

1. `cd apps/docs && yarn refresh-everything && yarn check-links` —
should pass with 0 broken links (warnings only)
2. `yarn check-links --fail` — same result but would exit 1 if any
broken links existed
3. Manually add a broken link to a content file (e.g.
`[test](/nonexistent)`) and run `yarn check-links --fail` — should exit
1 with the broken link reported
4. Run `yarn build` from `apps/docs` — check-links runs with `--fail`
before `next build`
5. `yarn check-external-links` — checks all ~630 unique external URLs,
reports broken ones

- [ ] Unit tests
- [ ] End to end tests

### Release notes

- Fix 134 broken internal links across SDK docs, starter kits, and API
reference
- Add static broken link checker to docs build pipeline (replaces
linkinator)
- Add standalone external link checker script (`yarn
check-external-links`)
- Document `TypeAlias` and `Interface` members within API reference
namespaces

#8276)

In order to stop docs-only hotfixes from triggering unwanted npm patch
releases, this PR adds `yarn refresh-assets --force` before the
`getAnyPackageDiff()` check in `publish-patch.ts`.

### Root cause

PR #8204 added `.yarn/install-state.gz` to the CI cache. When Yarn
determines that the install state hasn't changed (e.g. `node_modules` is
already populated and no dependencies changed), it [skips lifecycle
scripts](https://yarnpkg.com/advanced/lifecycle-scripts) including
`postinstall` ([related
discussion](yarnpkg/berry#5924)). This
means the `postinstall` hook (`husky install && yarn refresh-assets`)
never runs.

Without `refresh-assets`, the gitignored asset directories in
`@tldraw/assets` (`embed-icons/`, `fonts/`, `icons/`, `translations/`)
don't exist on disk. The `getAnyPackageDiff()` guard runs `yarn pack`
which produces a tarball missing these dirs (14 files), while the
npm-published tarball has them (265 files) — always finding a diff,
always publishing.

**Before #8204 (working):** PR #8102 docs hotfix cherry-picked to v4.4.x
— publish-patch skipped correctly, no version bump.

**After #8204 (broken):** PRs #8263 and #8270 docs hotfixes
cherry-picked to v4.5.x — both triggered unwanted npm publishes (v4.5.1
and v4.5.2).

### Why this approach

Considered three options:
1. **Remove `install-state.gz` from cache** — doesn't actually help;
Yarn skips postinstall based on dependency changes, not just the state
file
2. **Add `refresh-assets` to the setup action** — overkill; lazyrepo
already auto-runs it as a dependency of `build`, `build-types`, and
`dev`
3. **Add `refresh-assets` to `publish-patch.ts`** — targeted fix
matching what `trigger-sdk-hotfix.ts` already does (line 98)

Option 3 is the right call. `publish-patch.ts` is the only workflow
confirmed broken — everything else is protected by either lazyrepo's
dependency graph or explicit `refresh-assets` calls in the workflow
YAML.

### Change type

- [x] `bugfix`

### Test plan

Verified locally:
1. Removed asset dirs to simulate CI with warm cache (no postinstall)
2. `yarn pack` on `@tldraw/assets` → 14 files
3. Ran `yarn refresh-assets --force`
4. `yarn pack` again → 265 files

On a release branch with only docs changes, `getAnyPackageDiff()` should
now return `null` → "No packages have changed, skipping release" → no
publish.

### Code changes

| Section        | LOC change |
| -------------- | ---------- |
| Config/tooling | +4 / -0    |