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/dict/bot-dict.ts

@@ -49,7 +49,7 @@ export const BotKinds = [
 export type BotKind = (typeof BotKinds)[number]["value"];
 
 /**
- * Every workspace has exactly one coordinator, created with the account. It
+ * Every user has exactly one coordinator, created with the account. It
  * coordinates the crew and hands work to the other bots.
  */
 export const CoordinatorBotName = "Coordinator";