Add cross-compilation support for Linux and Windows

- Add Docker-based build system for cross-compiling on Apple Silicon
- Create Dockerfiles for Linux x86_64 and ARM64, Windows x86_64
- Add build-all.sh script for automated multi-platform builds
- Configure cargo-deb and cargo-generate-rpm for Linux packaging
- Update README with cross-compilation instructions

Supported outputs:
- Linux x86_64: .deb, .rpm, .tar.gz
- Windows x86_64: .zip

Note: Linux ARM64 disabled due to upstream zune-jpeg NEON bug

.gitignore

@@ -1,5 +1,6 @@
 chat-summaries/
 target/
+dist/
 
 .DS_Store
 *.mp4