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/commands/ai.rs

@@ -1,2 +1,91 @@
-// AI provider commands — chat, summarize via Python sidecar
-// TODO: Implement when AI provider service is built
+use serde_json::{json, Value};
+
+use crate::sidecar::messages::IPCMessage;
+use crate::sidecar::SidecarManager;
+
+fn get_sidecar() -> Result<SidecarManager, String> {
+    let python_path = std::env::current_dir()
+        .map_err(|e| e.to_string())?
+        .join("../python")
+        .canonicalize()
+        .map_err(|e| format!("Cannot find python directory: {e}"))?;
+
+    let manager = SidecarManager::new();
+    manager.start(&python_path.to_string_lossy())?;
+    Ok(manager)
+}
+
+/// Send a chat message to the AI provider via the Python sidecar.
+#[tauri::command]
+pub fn ai_chat(
+    messages: Value,
+    transcript_context: Option<String>,
+    provider: Option<String>,
+) -> Result<Value, String> {
+    let manager = get_sidecar()?;
+
+    let request_id = uuid::Uuid::new_v4().to_string();
+    let mut payload = json!({
+        "action": "chat",
+        "messages": messages,
+        "transcript_context": transcript_context.unwrap_or_default(),
+    });
+
+    // If a specific provider is requested, set it first
+    if let Some(p) = provider {
+        let set_msg = IPCMessage::new(
+            &uuid::Uuid::new_v4().to_string(),
+            "ai.chat",
+            json!({ "action": "set_provider", "provider": p }),
+        );
+        let _ = manager.send_and_receive(&set_msg)?;
+    }
+
+    let msg = IPCMessage::new(&request_id, "ai.chat", payload);
+    let response = manager.send_and_receive(&msg)?;
+
+    if response.msg_type == "error" {
+        return Err(format!(
+            "AI error: {}",
+            response.payload.get("message").and_then(|v| v.as_str()).unwrap_or("unknown")
+        ));
+    }
+
+    Ok(response.payload)
+}
+
+/// List available AI providers.
+#[tauri::command]
+pub fn ai_list_providers() -> Result<Value, String> {
+    let manager = get_sidecar()?;
+
+    let request_id = uuid::Uuid::new_v4().to_string();
+    let msg = IPCMessage::new(
+        &request_id,
+        "ai.chat",
+        json!({ "action": "list_providers" }),
+    );
+
+    let response = manager.send_and_receive(&msg)?;
+    Ok(response.payload)
+}
+
+/// Configure an AI provider with API key/settings.
+#[tauri::command]
+pub fn ai_configure(provider: String, config: Value) -> Result<Value, String> {
+    let manager = get_sidecar()?;
+
+    let request_id = uuid::Uuid::new_v4().to_string();
+    let msg = IPCMessage::new(
+        &request_id,
+        "ai.chat",
+        json!({
+            "action": "configure",
+            "provider": provider,
+            "config": config,
+        }),
+    );
+
+    let response = manager.send_and_receive(&msg)?;
+    Ok(response.payload)
+}