Phase 5: AI provider system with local and cloud support

- Implement AIProvider base interface with chat() and is_available()
- Add LocalProvider connecting to bundled llama-server via OpenAI SDK
- Add OpenAIProvider for direct OpenAI API access
- Add AnthropicProvider for Anthropic Claude API
- Add LiteLLMProvider for multi-provider gateway
- Build AIProviderService with provider routing, auto-selection,
  and transcript context injection
- Add ai.chat IPC handler supporting chat, list_providers, set_provider,
  and configure actions
- Add ai_chat, ai_list_providers, ai_configure Tauri commands
- Build interactive AIChatPanel with message history, quick actions
  (Summarize, Action Items), and transcript context awareness
- Tests: 30 Python, 6 Rust, 0 Svelte errors

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

src-tauri/src/lib.rs

@@ -3,6 +3,7 @@ pub mod db;
 pub mod sidecar;
 pub mod state;
 
+use commands::ai::{ai_chat, ai_configure, ai_list_providers};
 use commands::export::export_transcript;
 use commands::project::{create_project, get_project, list_projects};
 use commands::transcribe::{run_pipeline, transcribe_file};
@@ -19,6 +20,9 @@ pub fn run() {
             transcribe_file,
             run_pipeline,
             export_transcript,
+            ai_chat,
+            ai_list_providers,
+            ai_configure,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");