Update README, add User Guide and Contributing docs

- README: Updated to reflect current architecture (decoupled app/sidecar),
  Ollama as local AI, CUDA support, split CI workflows
- USER_GUIDE.md: Complete how-to including first-time setup, transcription
  workflow, speaker detection setup, Ollama configuration, export formats,
  keyboard shortcuts, and troubleshooting
- CONTRIBUTING.md: Dev setup, project structure, conventions, CI/CD overview

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

CONTRIBUTING.md

@@ -0,0 +1,140 @@
+# Contributing to Voice to Notes
+
+Thank you for your interest in contributing! This guide covers how to set up the project for development and submit changes.
+
+## Development Setup
+
+### Prerequisites
+
+- **Node.js 20+** and npm
+- **Rust** (stable toolchain)
+- **Python 3.11+** with [uv](https://docs.astral.sh/uv/) (recommended) or pip
+- **System libraries (Linux only):**
+  ```bash
+  sudo apt install libgtk-3-dev libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf xdg-utils
+  ```
+
+### Clone and Install
+
+```bash
+git clone https://repo.anhonesthost.net/MacroPad/voice-to-notes.git
+cd voice-to-notes
+
+# Frontend
+npm install
+
+# Python sidecar
+cd python && pip install -e ".[dev]" && cd ..
+```
+
+### Running in Dev Mode
+
+```bash
+npm run tauri:dev
+```
+
+This runs the Svelte dev server + Tauri with hot-reload. The Python sidecar runs from your system Python (no PyInstaller needed in dev mode).
+
+### Building
+
+```bash
+# Build the Python sidecar (frozen binary)
+cd python && python build_sidecar.py --cpu-only && cd ..
+
+# Build the full app
+npm run tauri build
+```
+
+## Project Structure
+
+```
+src/                        # Svelte 5 frontend
+  lib/components/           # Reusable UI components
+  lib/stores/               # Svelte stores (app state)
+  routes/                   # SvelteKit pages
+src-tauri/                  # Rust backend (Tauri v2)
+  src/sidecar/              # Python sidecar lifecycle (download, extract, IPC)
+  src/commands/             # Tauri command handlers
+  src/db/                   # SQLite database layer
+python/                     # Python ML sidecar
+  voice_to_notes/           # Main package
+    services/               # Transcription, diarization, AI, export
+    ipc/                    # JSON-line IPC protocol
+    hardware/               # GPU/CPU detection
+.gitea/workflows/           # CI/CD pipelines
+docs/                       # Documentation
+```
+
+## How It Works
+
+The app has three layers:
+
+1. **Frontend (Svelte)** — UI, audio playback (wavesurfer.js), transcript editing (TipTap)
+2. **Backend (Rust/Tauri)** — Desktop integration, file access, SQLite, sidecar process management
+3. **Sidecar (Python)** — ML inference (faster-whisper, pyannote.audio), AI chat, export
+
+Rust and Python communicate via **JSON-line IPC** over stdin/stdout pipes. Each request has an `id`, `type`, and `payload`. The Python sidecar runs as a child process managed by `SidecarManager` in Rust.
+
+## Conventions
+
+### Rust
+- Follow standard Rust conventions
+- Run `cargo fmt` and `cargo clippy` before committing
+- Tauri commands go in `src-tauri/src/commands/`
+
+### Python
+- Python 3.11+, type hints everywhere
+- Use `ruff` for linting: `ruff check python/`
+- Tests with pytest: `cd python && pytest`
+- IPC messages: JSON-line format with `id`, `type`, `payload` fields
+
+### TypeScript / Svelte
+- Svelte 5 runes (`$state`, `$derived`, `$effect`)
+- Strict TypeScript
+- Components in `src/lib/components/`
+- State in `src/lib/stores/`
+
+### General
+- All timestamps in milliseconds (integer)
+- UUIDs as primary keys in the database
+- Don't bundle API keys or secrets — those are user-configured
+
+## Submitting Changes
+
+1. Fork the repository
+2. Create a feature branch: `git checkout -b my-feature`
+3. Make your changes
+4. Test locally with `npm run tauri:dev`
+5. Run linters: `cargo fmt && cargo clippy`, `ruff check python/`
+6. Commit with a clear message describing the change
+7. Open a Pull Request against `main`
+
+## CI/CD
+
+Pushes to `main` automatically:
+- Bump the app version and create a release (`release.yml`)
+- Build app installers for all platforms
+
+Changes to `python/` also trigger sidecar builds (`build-sidecar.yml`).
+
+## Areas for Contribution
+
+- UI/UX improvements
+- New export formats
+- Additional AI provider integrations
+- Performance optimizations
+- Accessibility improvements
+- Documentation and translations
+- Bug reports and testing on different platforms
+
+## Reporting Issues
+
+Open an issue on the [repository](https://repo.anhonesthost.net/MacroPad/voice-to-notes/issues) with:
+- Steps to reproduce
+- Expected vs actual behavior
+- Platform and version info
+- Sidecar logs (`%LOCALAPPDATA%\com.voicetonotes.app\sidecar.log` on Windows)
+
+## License
+
+By contributing, you agree that your contributions will be licensed under the [MIT License](LICENSE).