refactor(app): unified panel state machine for mobile sidebars

Replace separate sidebar stores with a unified panel store that uses a
discriminated union state machine on mobile. This makes it impossible
for both the agent list and file explorer sidebars to be open at the
same time on mobile.

Mobile state machine (mobileView):
- 'agent': Main agent view (no overlay panel)
- 'agent-list': Agent list sidebar (left overlay)
- 'file-explorer': File explorer sidebar (right overlay)

Desktop retains independent boolean toggles since sidebars sit
alongside content rather than overlaying it.

Key changes:
- Created stores/panel-store.ts with unified state
- Deleted stores/sidebar-store.ts and explorer-sidebar-store.ts
- Updated all components to use new panel store
- Animation contexts derive isOpen from unified state

packages/server/src/services/agent-title-generator.ts

@@ -3,15 +3,13 @@ import { createOpenAI } from "@ai-sdk/openai";
 import { z } from "zod";
 import type { AgentTimelineItem } from "../server/agent/agent-sdk-types.js";
 import { curateAgentActivity } from "../server/agent/activity-curator.js";
-import { getRootLogger } from "../server/logger.js";
-
-const logger = getRootLogger().child({ module: "agent-title-generator" });
+import type pino from "pino";
 
 let openai: ReturnType<typeof createOpenAI> | null = null;
 
-export function initializeTitleGenerator(apiKey: string): void {
+export function initializeTitleGenerator(logger: pino.Logger, apiKey: string): void {
   openai = createOpenAI({ apiKey });
-  logger.info("Agent title generator initialized");
+  logger.child({ action: "initialize" }).info("Agent title generator initialized");
 }
 
 export function isTitleGeneratorInitialized(): boolean {
@@ -23,9 +21,11 @@ export function isTitleGeneratorInitialized(): boolean {
  * Returns a 3-5 word title similar to ChatGPT/Claude.ai
  */
 export async function generateAgentTitle(
+  logger: pino.Logger,
   timeline: AgentTimelineItem[],
   cwd: string
 ): Promise<string> {
+  const titleLogger = logger.child({ action: "generate" });
   if (!openai) {
     throw new Error("Title generator not initialized");
   }
@@ -59,11 +59,11 @@ ${activityContext}`,
       temperature: 0.7,
     });
 
-    logger.debug({ title: object.title }, "Generated agent title");
+    titleLogger.debug({ title: object.title }, "Generated agent title");
 
     return object.title;
   } catch (err) {
-    logger.error({ err }, "Failed to generate agent title");
+    titleLogger.error({ err }, "Failed to generate agent title");
     return "New Agent";
   }
 }