[Bug] Windows: Projects Remote file tree empty — git-credential-nostr path mangled by MinGW bash #3025

Describe the bug
On Windows, the Projects Remote file view is empty and Sync/Clone fails. Authentication never succeeds because the absolute git-credential-nostr path Buzz injects into credential.helper uses backslashes, which Git for Windows' MinGW bash treats as escape sequences and strips.

Example error:

Could not fetch repository.
Cloning into 'C:\Users\<user>\AppData\Local\Temp\tmpXXXXX\repo'...
C:\Users\<user>\AppData\Local\Buzz\git-credential-nostr.exe get: line 1:
C:Users<user>AppDataLocalBuzzgit-credential-nostr.exe: command not found
fatal: could not read Username for 'https://<relay>/git/<pubkey>/<repo>':
terminal prompts disabled

The same relay/repo works on macOS without extra configuration.

Root cause (short)
Buzz sets credential.helper from Path::display(), which on Windows yields C:\...\git-credential-nostr.exe. Git for Windows invokes helpers via sh.exe; bash mangles the path → helper not found → NIP-98 auth fails → Remote blobless clone fails → empty tree.

Projects git also sets GIT_CONFIG_GLOBAL=/dev/null, so user ~/.gitconfig workarounds do not apply.

This is not a missing/stub helper binary — the shipped git-credential-nostr.exe is functional once the path is passed with forward slashes.

Steps to reproduce

1. Install Buzz on Windows (Git for Windows required)
2. Connect to a Buzz relay that has a repository with at least one pushed branch
3. Open Projects → select the repository → switch to Remote
4. Observe an empty file tree
5. Press Sync / Clone and observe the mangled-path / command not found error above

Expected behavior
Remote view shows the repository file tree, and Sync/Clone authenticates via git-credential-nostr the same as on macOS.

Version and platform

• Buzz version: local build from fix branch / 0.4.26 NSIS (also reproduces on prior Windows installers)
• OS: Windows 11
• Git: Git for Windows 2.55.x

Logs / additional context
Reproduced by simulating Buzz's GIT_CONFIG_* injection:

• Backslash helper path → exact command not found mangling
• Forward-slash helper path (C:/Users/.../git-credential-nostr.exe) → helper runs successfully

Fix PR
#3023