Fix sidecar builds: macOS CUDA resolution and Windows uv install

macOS: pyproject.toml's [tool.uv.sources] forces torch from the CUDA
index which has no macOS ARM wheels. Use `uv sync --no-sources` to
bypass this and get torch from PyPI (which includes MPS support).

Windows: Add additional uv PATH locations ($LOCALAPPDATA\uv\bin) for
robustness with different runner environments.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-sidecar.yml

@@ -141,7 +141,7 @@ jobs:
 
       - name: Build sidecar (CUDA)
         run: |
-          uv sync
+          uv sync --frozen || uv sync
           uv run pyinstaller local-transcription-headless.spec
 
       - name: Package sidecar (CUDA)
@@ -151,7 +151,6 @@ jobs:
       - name: Build sidecar (CPU)
         run: |
           rm -rf dist/local-transcription-backend build/
-          # Install CPU-only PyTorch
           uv pip install torch torchaudio --index-url https://download.pytorch.org/whl/cpu --force-reinstall
           uv run pyinstaller local-transcription-headless.spec
 
@@ -228,7 +227,17 @@ jobs:
             Write-Host "uv already installed: $(uv --version)"
           } else {
             irm https://astral.sh/uv/install.ps1 | iex
-            echo "$env:USERPROFILE\.local\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+            # Add both possible uv install locations to PATH
+            $uvPaths = @(
+              "$env:USERPROFILE\.local\bin",
+              "$env:USERPROFILE\.cargo\bin",
+              "$env:LOCALAPPDATA\uv\bin"
+            )
+            foreach ($p in $uvPaths) {
+              if (Test-Path $p) {
+                echo $p | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+              }
+            }
           }
 
       - name: Set up Python
@@ -245,7 +254,8 @@ jobs:
       - name: Build sidecar (CUDA)
         shell: powershell
         run: |
-          uv sync
+          uv sync --frozen
+          if ($LASTEXITCODE -ne 0) { uv sync }
           uv run pyinstaller local-transcription-headless.spec
 
       - name: Package sidecar (CUDA)
@@ -356,9 +366,10 @@ jobs:
 
       - name: Build sidecar (CPU)
         run: |
-          # Install CPU-only PyTorch for macOS (MPS support included in default torch)
-          uv sync
-          uv pip install torch torchaudio --index-url https://download.pytorch.org/whl/cpu --force-reinstall
+          # --no-sources bypasses pyproject.toml's [tool.uv.sources] which forces
+          # torch from the CUDA index (no macOS ARM wheels there)
+          # Default PyPI torch includes MPS (Apple Silicon GPU) support
+          uv sync --no-sources
           uv run pyinstaller local-transcription-headless.spec
 
       - name: Package sidecar (CPU)