add per-agent permission-mode badge to the cockpit roster

Each roster row shows a D/A/P mode badge reflecting the session's live
permission mode. Click cycles the safe trio default -> acceptEdits ->
plan and sends a set_permission_mode control_request to that session
(mirrors interrupt(); fire-and-forget). bypassPermissions is a footgun,
so it is reachable only on Shift-click and behind an inline confirm. A
clide.agent.set-permission-mode command gives the CLI parity.

T-181.

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

lib/builtin/claude/src/stream_json_session.dart

@@ -592,6 +592,22 @@ class StreamJsonSession {
     }));
   }
 
+  /// Set the session's permission mode (T-181, D-77). Sends a
+  /// `set_permission_mode` control_request; fire-and-forget, mirroring
+  /// [interrupt]. [mode] must be one of the claude-recognised strings:
+  /// `default`, `acceptEdits`, `plan`, `bypassPermissions`.
+  ///
+  /// The safe trio (default → acceptEdits → plan → default) is cycled by the
+  /// cockpit badge's plain click; bypassPermissions is reachable only via a
+  /// confirmed shift-click (T-181).
+  void setPermissionMode(String mode) {
+    _proc.writeLine(jsonEncode({
+      'type': 'control_request',
+      'request_id': 'set-perm-${_localSeq++}',
+      'request': {'subtype': 'set_permission_mode', 'mode': mode},
+    }));
+  }
+
   Future<void> dispose() async {
     await _sub?.cancel();
     await _proc.kill();