Remove CUDA sidecar builds, keep CPU + Cloud only

CUDA sidecars are ~2GB and too slow to upload from the Windows runner.
Cloud (Deepgram) provides faster transcription anyway. Removed:

- CUDA build steps from Windows and Linux sidecar workflows
- CUDA option from the SidecarSetup download screen

Remaining sidecar variants:
- Cloud (Deepgram): ~50 MB - recommended for most users
- Local CPU: ~500 MB - for offline/privacy use

CUDA can be revisited once the managed Deepgram service is ready.

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

.gitea/workflows/build-sidecar-linux.yml

@@ -40,21 +40,11 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y portaudio19-dev
 
-      - name: Build sidecar (CUDA)
-        run: |
-          uv sync --frozen || uv sync
-          uv run pyinstaller local-transcription-headless.spec
-
-      - name: Package sidecar (CUDA)
-        run: |
-          cd dist/local-transcription-backend && zip -9 -r ../../sidecar-linux-x86_64-cuda.zip .
-
       - name: Build sidecar (CPU)
+        env:
+          UV_NO_SOURCES: "1"
         run: |
-          rm -rf dist/local-transcription-backend build/
-          uv pip install torch torchaudio --index-url https://download.pytorch.org/whl/cpu --force-reinstall
-          # Run pyinstaller directly from venv to prevent uv run from
-          # re-resolving torch back to the CUDA version via pyproject.toml sources
+          uv sync
           .venv/bin/pyinstaller local-transcription-headless.spec
 
       - name: Package sidecar (CPU)