Add workspaces, computers, bot memory and the bots queue

- Schema: workspaces (+ workspace_bots, workspace_computers), containers,
  computers, bot_computers, bots.memory, workspaces.system_prompt, and
  bots_queue as a bun-sqlite isQueue table
- Main computer (and its container record) ensured with the coordinator on
  signup, seed and /admin/bots; the coordinator's access to it is locked
- Effective computer access: direct grants plus workspace computers
- Full bot prompt: core instructions, workspace prompts, then memory;
  bots can rewrite their memory and system prompt
- Queue helpers on the native BunSQLite.queue API, plus a handler that
  heartbeats, serializes per computer, recovers after restarts, reports
  lost jobs, supports cancelling and pushes outcomes over the WebSocket
- Enable SQLite foreign keys at startup so schema cascades fire
- Prune finished jobs daily

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/data/coordinator-system-prompt.ts

@@ -2,8 +2,8 @@ import { SiteData } from "./site-data";
 
 /**
  * The coordinator's default core instructions (markdown), attached when the
- * coordinator is created. Stored per bot in `bots.system_prompt`, so a
- * workspace can edit its own copy without touching this default.
+ * coordinator is created. Stored per bot in `bots.system_prompt`, so each
+ * coordinator can edit its own copy without touching this default.
  */
 export const CoordinatorSystemPrompt = `# You are the Coordinator