Add vim list nav, fix window-title padding toggle, widen title spacing

TUI:
- VimListView: j/k now move down/up in the project and session lists
  (arrow keys still work); used by both list widgets.

tmux status bar:
- Widen the gap between window cells via a 2-space window-status-separator
  (WINDOW_STATUS_SEPARATOR).
- Fix the current-window cell toggling between padded " 1: name " and
  unpadded "1: name". The per-window status format is static, but
  set_window_label re-asserted it on every 3s poll — letting a competing
  writer (e.g. a stale TUI process running older code with a differently
  padded format) flip the cell each cycle. The format is now owned by a
  single write-once path (new_window at creation, apply_theme for existing
  windows); the poll updates only the dynamic @hqt_label.

Also lands pre-staged scaffolding: AGENTS.md quality gate, TODO.md backlog,
and ty dev dependency.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pyproject.toml

@@ -24,4 +24,12 @@ dev = [
     "pytest-asyncio>=0.24",
     "ruff>=0.8",
     "textual-dev>=1.0",
+    "ty>=0.0.47",
+]
+
+[tool.hqt.quality]
+required_after_code_or_test_changes = [
+    "uv run ruff format src tests",
+    "uv run ruff check src tests",
+    "uv run ty check",
 ]