process sidecar: independent process manager for long-running work

Introduces a separate Bun process (port 5100) that owns all spawned
processes and long-running work, so the API server can restart freely
without disrupting active sessions.

The sidecar owns:
- Anthropic proxy (port 5051) with persisted secret across restarts
- Claude Code process spawning and session tracking (--resume support)
- Pi agent spawning and RPC lifecycle (prompt/abort/thinking)
- Job queue engine (lane processing, retries, notifications)

The API server becomes a thin client that forwards commands over a
single WebSocket connection with auto-reconnect. send-claude-code.ts
goes from 550 lines of spawn logic to 73 lines of sidecar delegation.

State persisted to data/sidecar/state.json every 30s and on shutdown.
Lockfile prevents duplicate instances. See SIDECAR.md for full docs
and manual testing procedures.

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

src/server.tsx

@@ -12,7 +12,7 @@ import { desktopWebsocket } from './servers/api/desktop/websocket';
 import { findEntryByProxyId, touchEntry } from './servers/api/dev-server/router';
 import officerWeb from './apps/officer-web/index.html';
 import { startBrowserRelay } from './servers/api/browser/relay';
-import { startAnthropicProxy } from './servers/api/anthropic-proxy';
+import { initSidecarClient } from './servers/sidecar-client';
 import { toShellUsername } from './servers/data-path';
 
 const { PORT = '5000' } = process.env;
@@ -229,11 +229,8 @@ try {
   console.error('[browser-relay] failed to start:', err instanceof Error ? err.message : err);
 }
 
-try {
-  startAnthropicProxy();
-} catch (err) {
-  console.error('[anthropic-proxy] failed to start:', err instanceof Error ? err.message : err);
-}
+// Connect to process sidecar (owns proxy, Claude Code, Pi, queue)
+initSidecarClient();
 
 
 void initTerminalSidecars();