always run pi as the service user, drop the sudo -u branch

- the sandbox already drops privileges to the OS user (id -un), so pi-bridge was
  the only code path that switched to a per-user unix account
- the four accounts it targeted (andrepadez, john-wick, fedra, miguelbenoliel)
  are vestigial: created by scripts/provision-existing-users.sh, with no home
  dirs, no files, no processes. the only live account is pastilhas@officer.dev,
  which maps to the service user, so isServiceUser was always true and the
  sudo -u branch could never fire
- add TODO.md tracking the leftover username plumbing, the useradd script, known
  bugs (task-executor relative cwd, bootstrap pi EEXIST), and the ufw 9010 rule

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

TODO.md

@@ -0,0 +1,53 @@
+# TODO
+
+Deferred work. Context: Officer is collapsing from multi-tenant / open-source-ready to a
+**single-user platform**. Treat multi-tenant indirection as accidental complexity, not a requirement.
+
+## Single-user cleanup
+
+- [ ] **Remove dead `username` plumbing.** `pi-bridge.spawnPi` no longer uses `username` — it always
+      runs as the service user. But the handlers still compute `toShellUsername(...)` and thread it
+      through `sendAndAwait` → `spawnOptions`, where nothing reads it. `send-claude-code` declares
+      `username` (lines 8, 36) without using it. Typechecks clean today (excess-property checks don't
+      fire on variables), so it silently *looks* load-bearing.
+      Touches: `channels/{whatsapp,telegram,discord}/handler.ts`, `channels/send-and-await.ts`,
+      `channels/send-claude-code.ts`. After this, `toShellUsername` has one caller left
+      (`provision.ts` → `generateClaudeSettings`) and may be inlinable.
+
+- [ ] **Delete or gut `scripts/provision-existing-users.sh`.** Line ~100 runs
+      `sudo useradd -d "$HOME_DIR" -s /bin/zsh -M "$shell_user"`. This is what created the four
+      vestigial Unix accounts (`andrepadez`, `john-wick`, `fedra`, `miguelbenoliel`) that cluttered
+      the lightdm greeter. Nothing in the server creates Unix users; if this script runs again they
+      come back.
+
+- [ ] **Collapse the rest of the multi-tenant machinery.** Candidates, in rough order of payoff:
+      roles (`Super Admin`/`Member`), the sandboxed-vs-unsandboxed path split, per-email home dirs
+      under `dev-data/{email}/home`, per-user server state (dock, user apps, AppRegistry keyed by
+      email), and auth (passkeys-per-origin, JWT signin, unmounted `PasskeyGate`).
+
+## Known bugs
+
+- [ ] **Convert Audio task fails with `ENOENT: posix_spawn 'bash'`.** Misleading error — the real
+      cause is a *relative* `cwd` passed to `Bun.spawn` (ENOENT fires when the child's cwd doesn't
+      exist, not when the binary is missing). Fix is in `api/tasks/task-executor.ts`: resolve
+      `msg.cwd` against the user's home when it isn't absolute
+      (`isAbsolute(msg.cwd) ? msg.cwd : join(homeDir, msg.cwd)`). Was written and verified once, then
+      discarded in a working-tree cleanup.
+
+- [ ] **`bootstrap.ts` runs `npm install -g` for Pi on every boot.** `findPiPackageDir` checks stale
+      paths and an outdated package name, so `installPi` always fires and floods the logs with
+      `EEXIST` noise. Should detect `@earendil-works/pi-coding-agent` at the real npm prefix.
+
+## Infra (alpha)
+
+- [ ] **`ufw` blocks port 9010 on the LAN.** Default deny incoming; only `22/tcp`, `80/tcp`,
+      `443/tcp`, and everything on `tailscale0` are allowed — so `http://192.168.47.196:9010` is
+      unreachable from the LAN while localhost and Tailscale work.
+      Fix: `sudo ufw allow from 192.168.47.0/24 to any port 9010 proto tcp`
+
+## Backburner
+
+- [ ] **Music tagging feature** (`/music`, Mp3tag-inspired). v1 was scoped as a two-panel workspace —
+      file browser left, table right, single "Load" context-menu item flattening audio files into the
+      table. Discarded before completion; would need `GET /file-browser/flatten-audio`, a
+      `useFilesAPI.flattenAudio` method, and the Music app panel rebuilt from scratch.