feat(cli): real auth, delete commands, api-keys, JSON output, env override

Address the review findings on the CLI surface:

* `pic login` now prompts for username + password and POSTs to
  `/api/v1/admin/auth/login`. `--token` (and `PICLOUD_TOKEN`) still
  works for paste-a-bearer flows (CI, long-lived API keys). Falls
  back to a plain stdin read when no controlling tty is attached.
* `pic logout` revokes the session server-side and deletes the local
  credentials file. Idempotent.
* `PICLOUD_URL` / `PICLOUD_TOKEN` now override the on-disk credentials
  file for every command via `config::resolve`, not just for
  `pic login`. Matches gcloud/aws/kubectl semantics.
* New commands: `pic apps delete [--force]`, `pic apps show`,
  `pic scripts delete`, `pic api-keys mint|ls|rm`, plus top-level
  `pic invoke` / `pic deploy` shortcuts.
* `pic scripts ls` (no `--app`) now issues a single
  `GET /admin/scripts` + one `apps_list` in parallel and joins
  client-side, instead of walking N+1 per-app calls that aborted on
  the first 404 — the bug the test suite was retrying around.
* Global `--output tsv|json` flag wired through every list/show and
  through `whoami` / `logs`. TSV stays pipe-friendly; JSON is a real
  array of objects (or a flat object for single-row views).
* `whoami` and `logs` now emit labeled output instead of headerless
  tab lines, consistent with the existing `apps ls` / `scripts ls`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -1535,6 +1535,7 @@ version = "0.6.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
+ "chrono",
  "clap",
  "directories",
  "libc",