unify agent items into a flat file-based store, drop the marketplace

Replace the marketplace service dependency and the native/global/user
scope tiers with a single external directory ($OFFICER_ITEMS_DIR) holding
skills, tools, tasks, processes and extensions as plain files.

- tasks move from Postgres to TASK.md files (new file-backed task layer);
  task editing now works, which the DB path never supported
- skills/tools/processes collapse into one shared file router (single dir)
- remove the marketplace client (sync-marketplace/sync-version) and the
  boot-time sync; pi-bridge/pi-manager/sandbox point at the flat store
- drop the dead tasks + vestigial skills/tools/processes/extensions +
  item_chats tables (migration 0004)
- one-time migration script exports DB tasks and consolidates disk items

Migration verified: all 6 tasks round-trip through the runtime parser
identically to their DB rows (pipeline steps, triggers, script impls and
agentic bodies all intact).

NOTE: not yet functionally tested end-to-end — every item (each task mode,
tool, skill, extension) still needs to be run/exercised in the app before
this is trusted. To be done manually.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/servers/bootstrap.ts

@@ -1,8 +1,7 @@
 import { mkdirSync } from 'node:fs';
 import { join } from 'node:path';
 import { homedir } from 'node:os';
-import { DATA_PATH } from './data-path';
-import { syncMarketplaceTools, syncMarketplaceTasks } from './sync-marketplace';
+import { DATA_PATH, ensureItemDirs } from './data-path';
 import { ensureToolLoader } from './ensure-tool-loader';
 // Queue is now owned by the sidecar process
 import { startDiscordBotIfConfigured } from './channels/discord/bot';
@@ -10,6 +9,7 @@ import { startTelegramBotIfConfigured } from './channels/telegram/bot';
 import { startWhatsAppBotIfConfigured } from './channels/whatsapp/bot';
 
 mkdirSync(DATA_PATH, { recursive: true });
+ensureItemDirs();
 
 /** Check common locations for the Pi package directory. */
 async function findPiPackageDir(): Promise<string | null> {
@@ -67,8 +67,6 @@ async function installPi(): Promise<boolean> {
     }
   }
 
-  await syncMarketplaceTools();
-  await syncMarketplaceTasks();
   ensureToolLoader();
   // Queue is initialized by the sidecar process