feat: add interactive terminal and dev server management

Add new features for interactive terminal sessions and dev server control:

Terminal Component:
- New Terminal.tsx component using xterm.js for full terminal emulation
- WebSocket-based PTY communication with bidirectional I/O
- Cross-platform support (Windows via winpty, Unix via built-in pty)
- Auto-reconnection with exponential backoff
- Fix duplicate WebSocket connection bug by checking CONNECTING state
- Add manual close flag to prevent auto-reconnect race conditions
- Add project tracking to avoid duplicate connects on initial activation

Dev Server Management:
- New DevServerControl.tsx for starting/stopping dev servers
- DevServerManager service for subprocess management
- WebSocket streaming of dev server output
- Project configuration service for reading package.json scripts

Backend Infrastructure:
- Terminal router with WebSocket endpoint for PTY I/O
- DevServer router for server lifecycle management
- Terminal session manager with callback-based output streaming
- Enhanced WebSocket schemas for terminal and dev server messages

UI Integration:
- New Terminal and Dev Server tabs in the main application
- Updated DebugLogViewer with improved UI and functionality
- Extended useWebSocket hook for terminal message handling

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

ui/src/lib/api.ts

@@ -21,6 +21,8 @@ import type {
   Settings,
   SettingsUpdate,
   ModelsResponse,
+  DevServerStatusResponse,
+  DevServerConfig,
 } from './types'
 
 const API_BASE = '/api'
@@ -301,3 +303,33 @@ export async function updateSettings(settings: SettingsUpdate): Promise<Settings
     body: JSON.stringify(settings),
   })
 }
+
+// ============================================================================
+// Dev Server API
+// ============================================================================
+
+export async function getDevServerStatus(projectName: string): Promise<DevServerStatusResponse> {
+  return fetchJSON(`/projects/${encodeURIComponent(projectName)}/devserver/status`)
+}
+
+export async function startDevServer(
+  projectName: string,
+  command?: string
+): Promise<{ success: boolean; message: string }> {
+  return fetchJSON(`/projects/${encodeURIComponent(projectName)}/devserver/start`, {
+    method: 'POST',
+    body: JSON.stringify({ command }),
+  })
+}
+
+export async function stopDevServer(
+  projectName: string
+): Promise<{ success: boolean; message: string }> {
+  return fetchJSON(`/projects/${encodeURIComponent(projectName)}/devserver/stop`, {
+    method: 'POST',
+  })
+}
+
+export async function getDevServerConfig(projectName: string): Promise<DevServerConfig> {
+  return fetchJSON(`/projects/${encodeURIComponent(projectName)}/devserver/config`)
+}