feat: add dev server log panel with real-time streaming

Add the ability to view dev server logs in a dedicated panel with:
- Real-time log streaming via WebSocket events
- ANSI color support using xterm.js
- Scrollback buffer (50KB) for log history on reconnect
- Output throttling to prevent UI flooding
- "View Logs" option in worktree dropdown menu

Server changes:
- Add scrollback buffer and event emission to DevServerService
- Add GET /api/worktree/dev-server-logs endpoint
- Add dev-server:started, dev-server:output, dev-server:stopped events

UI changes:
- Add reusable XtermLogViewer component
- Add DevServerLogsPanel dialog component
- Add useDevServerLogs hook for WebSocket subscription

Closes #462

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/server/src/routes/worktree/index.ts

@@ -33,6 +33,7 @@ import { createMigrateHandler } from './routes/migrate.js';
 import { createStartDevHandler } from './routes/start-dev.js';
 import { createStopDevHandler } from './routes/stop-dev.js';
 import { createListDevServersHandler } from './routes/list-dev-servers.js';
+import { createGetDevServerLogsHandler } from './routes/dev-server-logs.js';
 import {
   createGetInitScriptHandler,
   createPutInitScriptHandler,
@@ -97,6 +98,11 @@ export function createWorktreeRoutes(events: EventEmitter): Router {
   );
   router.post('/stop-dev', createStopDevHandler());
   router.post('/list-dev-servers', createListDevServersHandler());
+  router.get(
+    '/dev-server-logs',
+    validatePathParams('worktreePath'),
+    createGetDevServerLogsHandler()
+  );
 
   // Init script routes
   router.get('/init-script', createGetInitScriptHandler());

apps/server/src/routes/worktree/routes/dev-server-logs.ts

@@ -0,0 +1,52 @@
+/**
+ * GET /dev-server-logs endpoint - Get buffered logs for a worktree's dev server
+ *
+ * Returns the scrollback buffer containing historical log output for a running
+ * dev server. Used by clients to populate the log panel on initial connection
+ * before subscribing to real-time updates via WebSocket.
+ */
+
+import type { Request, Response } from 'express';
+import { getDevServerService } from '../../../services/dev-server-service.js';
+import { getErrorMessage, logError } from '../common.js';
+
+export function createGetDevServerLogsHandler() {
+  return async (req: Request, res: Response): Promise<void> => {
+    try {
+      const { worktreePath } = req.query as {
+        worktreePath?: string;
+      };
+
+      if (!worktreePath) {
+        res.status(400).json({
+          success: false,
+          error: 'worktreePath query parameter is required',
+        });
+        return;
+      }
+
+      const devServerService = getDevServerService();
+      const result = devServerService.getServerLogs(worktreePath);
+
+      if (result.success && result.result) {
+        res.json({
+          success: true,
+          result: {
+            worktreePath: result.result.worktreePath,
+            port: result.result.port,
+            logs: result.result.logs,
+            startedAt: result.result.startedAt,
+          },
+        });
+      } else {
+        res.status(404).json({
+          success: false,
+          error: result.error || 'Failed to get dev server logs',
+        });
+      }
+    } catch (error) {
+      logError(error, 'Get dev server logs failed');
+      res.status(500).json({ success: false, error: getErrorMessage(error) });
+    }
+  };
+}