add clide status orientation snapshot; close Epic C (T-221)

clide status returns a one-shot snapshot for an orienting agent: the
workspace root, a git summary (branch/ahead/behind/clean/counts), the
active editor buffer + selection, the read-only readers' viewed docs
(new ReaderNavRegistry.currentByReader, the T-220 fold), focusedFile,
the live view-pane list (T-219), and the layout (slots + visibility +
focus mode). Previously 'status' was an unknown command (exit 3).

The verb handler (status_command.dart) is a thin Flutter-free wrapper;
the snapshot is assembled in main.dart where the live kernel + subsystem
state is in scope, with readerNav captured post-boot. Composite shape is
verified live; the pieces are unit-tested.

Closes T-221 and T-218 (Epic C) under T-208 'Give Claude hands' --
the observe half of D-6 parity is now in place.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -22,6 +22,9 @@ heading, and (b) bumping `pubspec.yaml` `version:` in the same commit.
   composer is focused, a clickable mode badge in the status line, or the
   "Claude: Cycle permission mode" palette command — steps default → accept-edits
   → plan (bypass stays behind the cockpit's confirm). (T-226)
+- `clide status` — a one-shot orientation snapshot for agents: workspace, git
+  summary, active editor buffer + selection, viewed reader docs, the live panes
+  the user sees, and the layout. Previously an unknown command (exit 3). (T-221)
 - `clide pane list` now reflects the live GUI tabs the user sees (Claude, Files,
   Editor, viewers) alongside PTY panes — each with a stable id, slot, title, and
   active/visible state — by snapshotting the kernel panel layout at request time.