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/scrollback/render.rs

@@ -2536,7 +2536,7 @@ mod tests {
 
     #[test]
     fn markdown_wrapped_session_media_path_fully_linkified() {
-        // Regression: imagine-tool prose whose long session path soft-wraps
+        // Regression: media-tool prose whose long session path soft-wraps
         // across rows. The whole path must be clickable (one overlay region
         // per row, all pointing at the full file:// URL) — not just the
         // leading path fragment on the first row.
@@ -3285,7 +3285,7 @@ mod tests {
 
         let mut entries = vec![
             ScrollbackEntry::new(RenderBlock::ToolCall(ToolCallBlock::Other(
-                OtherToolCallBlock::new("image_gen", "saved image")
+                OtherToolCallBlock::new("media_tool", "saved image")
                     .with_media_ref(&image_path, false),
             ))),
             ScrollbackEntry::new(RenderBlock::execute_with_output(
@@ -4142,7 +4142,7 @@ mod tests {
         std::fs::write(&image_path, make_test_png(120, 120)).unwrap();
 
         let entry = ScrollbackEntry::new(RenderBlock::ToolCall(ToolCallBlock::Other(
-            OtherToolCallBlock::new("image_gen", "saved image").with_media_ref(&image_path, false),
+            OtherToolCallBlock::new("media_tool", "saved image").with_media_ref(&image_path, false),
         )));
         let viewport = Rect::new(0, 0, 80, 30);
         let result = render_with_scratch(std::slice::from_ref(&entry), viewport, 0, None);