fix(nix): ensure absolute bundle path in pre-sync backup (#204)

* fix(nix): ensure absolute bundle path in pre-sync backup (#203)

Use path.resolve() instead of conditional path.isAbsolute() check to
guarantee bundlePath is always absolute before passing to git -C. On
NixOS, relative paths were interpreted relative to the temp mirror
clone directory, causing "No such file or directory" errors.

Closes #203

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(nix): ensure absolute bundle path in pre-sync backup (#203)

Use path.resolve() instead of conditional path.isAbsolute() check to
guarantee bundlePath is always absolute before passing to git -C. On
NixOS, relative paths were interpreted relative to the temp mirror
clone directory, causing "No such file or directory" errors.

Extract resolveBackupPaths() for testability. Bump version to 3.10.1.

Closes #203

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* ci: drop macos matrix and only run nix build on main/tags

- Remove macos-latest from Nix CI matrix (ubuntu-only)
- Only run `nix build` on main branch and version tags, skip on PRs
- `nix flake check` still runs on all PRs for validation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/nix-build.yml

@@ -13,10 +13,7 @@ permissions:
 
 jobs:
   check:
-    strategy:
-      matrix:
-        os: [ubuntu-latest, macos-latest]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v4
@@ -34,4 +31,5 @@ jobs:
         run: nix flake show
 
       - name: Build package
+        if: github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/v')
         run: nix build --print-build-logs