Use max compression for sidecar zips to reduce upload size

zip -9 on Linux, 7z -mx=9 on Windows. Compression takes longer but
produces smaller files which upload faster over the network.

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

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

@@ -47,7 +47,7 @@ jobs:
 
       - name: Package sidecar (CUDA)
         run: |
-          cd dist/local-transcription-backend && zip -r ../../sidecar-linux-x86_64-cuda.zip .
+          cd dist/local-transcription-backend && zip -9 -r ../../sidecar-linux-x86_64-cuda.zip .
 
       - name: Build sidecar (CPU)
         run: |
@@ -59,7 +59,7 @@ jobs:
 
       - name: Package sidecar (CPU)
         run: |
-          cd dist/local-transcription-backend && zip -r ../../sidecar-linux-x86_64-cpu.zip .
+          cd dist/local-transcription-backend && zip -9 -r ../../sidecar-linux-x86_64-cpu.zip .
 
       - name: Upload to sidecar release
         env: