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/servers/api/queue/queue.ts

@@ -1,5 +1,5 @@
 import { createRouter } from '../../create-router';
-import { enqueue, cancelJob, readJob, listAllJobs } from '../../queue';
+import * as sidecar from '../../sidecar-client';
 import { NOT_FOUND } from '../../custom-errors';
 
 export const queueRouter = createRouter();
@@ -10,7 +10,7 @@ queueRouter.get('/jobs', async (ctx) => {
   const type = ctx.req.query('type');
   const status = ctx.req.query('status');
 
-  let jobs = await listAllJobs();
+  let jobs = await sidecar.listJobs();
   jobs = jobs.filter((j) => j.userId === user.email);
 
   if (lane) jobs = jobs.filter((j) => j.lane === lane);
@@ -21,7 +21,7 @@ queueRouter.get('/jobs', async (ctx) => {
 });
 
 queueRouter.get('/jobs/:id', async (ctx) => {
-  const job = await readJob(ctx.req.param('id'));
+  const job = await sidecar.getJob(ctx.req.param('id'));
   if (!job) throw NOT_FOUND('Job not found');
   return ctx.json(job);
 });
@@ -36,12 +36,12 @@ queueRouter.post('/jobs', async (ctx) => {
     notify?: boolean;
   };
 
-  const job = await enqueue({ lane, type, userId: user.email, meta, notify });
+  const job = await sidecar.enqueueJob({ lane, type, userId: user.email, meta, notify });
   return ctx.json(job, 201);
 });
 
 queueRouter.delete('/jobs/:id', async (ctx) => {
-  const job = await cancelJob(ctx.req.param('id'));
+  const job = await sidecar.cancelJob(ctx.req.param('id'));
   if (!job) throw NOT_FOUND('Job not found');
   return ctx.json(job);
 });