Phase 1 foundation: Tauri shell, Python sidecar, SQLite database

Tauri v2 + Svelte + TypeScript frontend:
- App shell with workspace layout (waveform, transcript, speakers, AI chat)
- Placeholder components for all major UI areas
- Typed stores (project, transcript, playback, AI)
- TypeScript interfaces matching the database schema
- Tauri bridge service with typed invoke wrappers
- svelte-check passes with 0 errors

Rust backend:
- Tauri v2 app entry point with command registration
- SQLite database layer (rusqlite with bundled SQLite)
  - Full schema: projects, media_files, speakers, segments, words,
    ai_outputs, annotations (with indexes)
  - Model structs with serde serialization
  - CRUD queries for projects, speakers, segments, words
  - Segment text editing preserves original text
  - Schema versioning for future migrations
  - 6 tests passing
- Command stubs for project, transcribe, export, AI, settings, system
- App state management

Python sidecar:
- JSON-line IPC protocol (stdin/stdout)
- Message types: IPCMessage, progress, error, ready
- Handler registry with routing and error handling
- Ping/pong handler for connectivity testing
- Service stubs: transcribe, diarize, pipeline, AI, export
- Provider stubs: local (llama-server), OpenAI, Anthropic, LiteLLM
- Hardware detection stubs
- 14 tests passing, ruff clean

Also adds:
- Testing strategy document (docs/TESTING.md)
- Validation script (scripts/validate.sh)
- Updated .gitignore for Svelte, Rust, Python artifacts

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

python/tests/test_handlers.py

@@ -0,0 +1,43 @@
+"""Tests for message handler routing."""
+
+from voice_to_notes.ipc.handlers import HandlerRegistry, ping_handler
+from voice_to_notes.ipc.messages import IPCMessage
+
+
+def test_ping_handler():
+    msg = IPCMessage(id="req-1", type="ping", payload={"hello": "world"})
+    response = ping_handler(msg)
+    assert response.type == "pong"
+    assert response.id == "req-1"
+    assert response.payload["echo"] == {"hello": "world"}
+
+
+def test_registry_routes_to_handler():
+    registry = HandlerRegistry()
+    registry.register("ping", ping_handler)
+    msg = IPCMessage(id="req-1", type="ping", payload={})
+    response = registry.handle(msg)
+    assert response is not None
+    assert response.type == "pong"
+
+
+def test_registry_unknown_type():
+    registry = HandlerRegistry()
+    msg = IPCMessage(id="req-1", type="nonexistent", payload={})
+    response = registry.handle(msg)
+    assert response is not None
+    assert response.type == "error"
+    assert response.payload["code"] == "unknown_type"
+
+
+def test_registry_handler_exception():
+    def bad_handler(msg: IPCMessage) -> IPCMessage:
+        raise ValueError("something broke")
+
+    registry = HandlerRegistry()
+    registry.register("bad", bad_handler)
+    msg = IPCMessage(id="req-1", type="bad", payload={})
+    response = registry.handle(msg)
+    assert response is not None
+    assert response.type == "error"
+    assert response.payload["code"] == "handler_error"