feat(vcs): PyCharm-style Commit view and one shared message dialog

- workbench/messages: one promise-based ask/confirm/confirmChecked/showError
  host replaces the per-feature confirm dialogs (app, services, vcs,
  project tree, keymap, run, database, find, LSP choice popup).
- Commit tool window: Commit | Shelf | Stash tabs as the title, IDEA's
  toolbar (Update Project, View Options, Select Opened File), Unversioned
  collapsed, Commit / Commit and Push on one row, empty-message error.
- Commit Options popup: author, sign-off, before-commit checks, Git hooks;
  vcs_commit takes CommitOptions (--author, --no-verify).
- Remove from Recent Projects asks first; refused history rewrites show an
  error dialog.

Claude-Session: https://claude.ai/code/session_01B65qLEKnkeYTGdbwhLpjCu

src/workbench/toolwindows/ToolWindows.module.css

@@ -327,6 +327,9 @@
   margin-left: 6px;
   overflow: hidden;
 }
+.headerContentOnly {
+  margin-left: 0;
+}
 .headerSpacer {
   flex: 1;
 }