add pipeline task system, agentic music tasks, copy buttons, and pi-bridge cleanup

- Pipeline mode: new task mode that chains agentic tasks sequentially with
  foreach/subdirectory iteration and skip_if conditions
- Pipeline executor backend (WebSocket at /api/tasks/pipeline/ws) with
  support for both Pi and Claude Code models
- Frontend PipelineRunner component with step progress, streaming output,
  and aggregate cost tracking
- New agentic tasks: prepare-discography, fetch-album-info, build-discography
  (pipeline combining both)
- Seed parser extended to handle pipeline steps in frontmatter config
- CopyButton component added to assistant bubbles, error bubbles, and
  tool input/output sections
- Removed obsolete SearXNG/Apify/browser relay code from pi-bridge

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

src/server.tsx

@@ -7,6 +7,7 @@ import { isTokenBlacklisted } from 'officerdb';
 import { terminalWebsocket } from './servers/api/terminal/websocket';
 import { piWebsocket } from './servers/api/pi/websocket';
 import { taskRunnerWebsocket } from './servers/api/tasks/task-executor';
+import { pipelineWebsocket } from './servers/api/tasks/pipeline-executor';
 import { cliampWebsocket } from './servers/api/cliamp/websocket';
 import { cliampAudioWebsocket } from './servers/api/cliamp/audio-ws';
 import { desktopWebsocket } from './servers/api/desktop/websocket';
@@ -24,7 +25,7 @@ type WSData = {
   email: string;
   username: string;
   role: string;
-  provider: 'terminal' | 'pi' | 'task-runner' | 'dev-server' | 'cliamp' | 'cliamp-audio' | 'desktop' | 'sidecar';
+  provider: 'terminal' | 'pi' | 'task-runner' | 'pipeline' | 'dev-server' | 'cliamp' | 'cliamp-audio' | 'desktop' | 'sidecar';
   sandboxed: boolean;
   sessionId?: string;
   cwd?: string;
@@ -118,6 +119,7 @@ const handlers: Record<string, any> = {
   terminal: terminalWebsocket,
   pi: piWebsocket,
   'task-runner': taskRunnerWebsocket,
+  pipeline: pipelineWebsocket,
   cliamp: cliampWebsocket,
   'cliamp-audio': cliampAudioWebsocket,
   desktop: desktopWebsocket,
@@ -189,7 +191,7 @@ const devServerWebsocket = {
 };
 handlers['dev-server'] = devServerWebsocket;
 
-async function upgradeWs(req: Request, server: any, provider: 'terminal' | 'pi' | 'task-runner' | 'cliamp' | 'cliamp-audio' | 'desktop') {
+async function upgradeWs(req: Request, server: any, provider: 'terminal' | 'pi' | 'task-runner' | 'pipeline' | 'cliamp' | 'cliamp-audio' | 'desktop') {
   const token = new URL(req.url).searchParams.get('token');
   if (!token) return new Response('Unauthorized', { status: 401 });
 
@@ -274,6 +276,7 @@ const server = serve({
       if (!ok) return new Response('Upgrade failed', { status: 500 });
     },
     '/api/tasks/run/ws': (req, server) => upgradeWs(req, server, 'task-runner'),
+    '/api/tasks/pipeline/ws': (req, server) => upgradeWs(req, server, 'pipeline'),
     '/api/terminal/ws': (req, server) => upgradeWs(req, server, 'terminal'),
     '/api/pi/chat/ws': (req, server) => upgradeWs(req, server, 'pi'),
     '/api/cliamp/ws': (req, server) => upgradeWs(req, server, 'cliamp'),