feat(vim): ex command-line overlay (:w :q :wq :x :e :N, ZZ) (T-407)

Under the Vim preset, `:` opens a transient one-line ex overlay running a
fixed v1 table; ZZ runs :wq directly. Completes the last built child of the
T-403 cross-pane vim layer (T-405 part 2 gt/gT still open).

- ExLineController + parseExCommand grammar + editor-targeted executors
  (lib/kernel/src/ex_line.dart); the overlay (lib/widgets/src/ex_line_overlay
  .dart) reuses the quick-open chrome, mounts in the root_shell Stack, and
  publishes the exline.open scope flag. Unknown commands flash + stay open;
  with no active buffer every command no-ops (2026-06-13 decision).
- :q closes the active tab via editor.close on its id — the registry promotes
  the next buffer and the split self-collapses on the last (2026-06-12
  decision); :w/:wq/:x/ZZ save (+close) the active buffer.
- :e <path> seeds quick-open (new QuickOpenController.open(seed:)); :N adds the
  editor.goto-line IPC/CLI verb (reuses _offsetForLine). Goto needs caret sync:
  EditorController now handles editor.selection-changed and the editor view
  moves the caret on a selection-only change.
- `:` and ZZ are typed intents; the editor matcher and PaneKeyNav now bubble
  unhandled typed intents to the app-root Actions, so they fire from any focus.
  vim.yaml binds `:`, ZZ (shift+z shift+z), and Esc-dismiss.

Tests: parser/controller/executors, editor.goto-line daemon tests,
selection-changed (controller + view), full overlay widget test. make test
green; analyze + format clean.

Also files T-441 (drop bold from the ticket-id card label) and T-442
(sub-agent renders as 3 cards instead of one bundle) under the T-276 UI epic.

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

assets/keymaps/vim.yaml

@@ -50,6 +50,11 @@ bindings:
   - intent: dismiss
     keys: escape
     when: quickOpen.open
+  # Ex command-line overlay (T-407): Esc dismisses it back to normal mode (the
+  # overlay's own EditableText handles Enter via onSubmitted).
+  - intent: dismiss
+    keys: escape
+    when: exline.open
   - intent: findInFiles.open
     keys: [ctrl+shift+f, meta+shift+f]
   - intent: focus.nextPanel
@@ -128,6 +133,18 @@ bindings:
     keys: [ctrl+w q, ctrl+w c]
     when: "vim.normal || vim.visual"
 
+  # ---- Ex command-line (T-407) -----------------------------------------
+  # `:` opens the transient ex overlay (`:w` `:q` `:wq` `:x` `:e <path>` `:N`);
+  # `ZZ` runs `:wq` directly. Both are typed app intents the editor's command
+  # matcher and a pane's nav matcher bubble to the app-root Actions, so they
+  # fire from any focus. Editor-targeted: no-op when no buffer is active.
+  - intent: exline.open
+    keys: shift+semicolon # :
+    when: vim.normal
+  - intent: exline.writeQuit
+    keys: shift+z shift+z # ZZ
+    when: vim.normal
+
   # ---- Mode transitions ------------------------------------------------
   - intent: command:vim.mode.visual
     keys: v