M2 audit: excise managed connectors and xAI media-gen tools

Managed connectors (grok.com MCP admin) removed root-and-branch:
- The managed-MCP fetch/injection pipeline is gone, including the whole
  kigi-shell-session-support crate (managed-config fetch client, gateway
  tool catalog + dispatch, header injection, refresh task), reactive
  managed re-auth, mcp_doctor's grok.com-source discovery, and the
  [managed_mcps] config surface.
- TUI: the 'Managed by grok.com' section, connectors URL/deep-link,
  Action::OpenManagedConnectors, and session_team_id are gone. Local MCP
  management (list/toggle/add/remove/auth/tools) is fully intact.
- Kept as LOCAL policy: managed-settings.json MCP allow/deny enforcement,
  the multi-source local MCP merge, folder-trust gating. PluginOrigin
  Project/User labels kept (they tag locally discovered plugin dirs).

imagine/media-gen tools (xAI image/video generation) removed:
- image_gen, image_edit, video_gen, image_to_video, reference_to_video
  implementations, registrations, ToolKind/ToolInput/Output variants
  (serde-safe), config plumbing end to end, ZDR video machinery,
  /imagine + /imagine-video commands and guidance text, the bundled
  imagine skill (added to legacy cleanup so user installs delete it),
  and the media-gen render path.
- Kept: image INPUT (paste/attach, [Image #N] meta, pdf/image fetch,
  clipboard wrap), generic media-ref rendering, and the generic tool
  401-retry machinery (tests renamed, assertions unweakened).
- deploy_app stays: it is a permanently-disabled local stub deploying
  nowhere.

121 files changed, 8 deleted. Gates: workspace check/clippy 0/0, fmt,
deny ok; suites green (tools 2554, shell 4862, tui 6608, workspace
1042). Remaining grok.com strings live only in the auth-method ids and
changelog archives (§9/M3 sweep).

crates/codegen/kigi-tui/src/slash/mod.rs

@@ -2555,19 +2555,19 @@ mod tests {
         let state = SlashState::default();
         let models = ModelState::default();
 
-        let text = "hi /imagine\n\n  /execute-plan";
-        let cursor = text.find("/imagine").unwrap() + "/imagine".len();
+        let text = "hi /compact\n\n  /execute-plan";
+        let cursor = text.find("/compact").unwrap() + "/compact".len();
         ctrl.refresh(&state, text, cursor, &models);
         let snapshot = state.snapshot();
         assert!(
             snapshot.cursor_in_command,
-            "cursor at end of /imagine must stay in command mode for Tab"
+            "cursor at end of /compact must stay in command mode for Tab"
         );
         assert_eq!(snapshot.args_range, None);
         assert_eq!(
             snapshot.command_range,
             Some(3..11),
-            "Tab must target /imagine, not the later /execute-plan token"
+            "Tab must target /compact, not the later /execute-plan token"
         );
     }