feat(dashboard,cli): update-check frequency, GitHub star button, more resizable modals

Update-check frequency (end-to-end)
- Add `updateCheckFrequency: "manual" | "on-startup" | "daily" | "weekly"`
  to GlobalSettings (default: "daily").
- Backend `performUpdateCheck` honors the frequency: TTL = day/week,
  `manual` returns cache or empty without hitting npm, `on-startup`
  refreshes once per process lifetime then serves cache. `/refresh`
  route forces network regardless.
- Settings → Updates surfaces a working `<select>` for the cadence,
  disabled when auto-checks are off entirely.
- Tests: 4 new cases covering ttlForFrequency mapping, weekly window,
  manual semantics, on-startup once-per-process behavior.

TUI update notice
- Read cached update result synchronously on TUI startup. When an
  update is available, render a yellow notice line on the splash and
  a colored ● next to the version in the status bar.

Settings modal header polish
- Add "Star on GitHub" pill (icon + Star + cached star count from the
  GitHub API, 1h localStorage TTL) and "Help" button (opens project
  Discussions). Both link to the Runfusion/Fusion repo.
- Star button auto-hides after the user clicks it (intent = star),
  tracked in localStorage `fusion:github-star-clicked`.
- Settings → General gets a "Show Star on GitHub button" checkbox so
  users can hide it preemptively. New global setting
  `showGitHubStarButton: boolean` (default true) gates rendering.

More resizable modals
- Task Detail modal: 85vh default, resize: both, persisted via
  useModalResizePersist (key `fusion:task-detail-modal-size`).
- Quick Chat FAB: full 8-direction resize (4 corners + 4 edges) via
  pointer-event handlers; persisted to
  `fusion:quick-chat-size-<projectId>`. Each handle has the right
  cursor + role="separator" for accessibility.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/components/SettingsModal.css

@@ -2,6 +2,60 @@
    Extracted from styles.css as part of the Sweep-3 CSS extraction effort.
    Imported by SettingsModal.tsx (and MemoryView.tsx for shared classes). */
 
+/* === Settings Modal header action buttons (Star on GitHub, Help) === */
+.settings-header-actions {
+  display: flex;
+  align-items: center;
+  gap: var(--space-xs);
+  margin-left: auto;
+  margin-right: var(--space-sm);
+}
+
+/* GitHub star button — split-pill layout: [Star half | Count half] */
+.settings-github-star-btn {
+  display: inline-flex;
+  align-items: stretch;
+  border: var(--btn-border-width) solid var(--border);
+  border-radius: var(--radius-pill);
+  background: var(--card);
+  color: var(--text);
+  font-size: 12px;
+  font-weight: 500;
+  text-decoration: none;
+  overflow: hidden;
+  transition:
+    border-color var(--transition-fast),
+    background var(--transition-fast);
+}
+
+.settings-github-star-btn:hover {
+  border-color: var(--text-muted);
+  background: var(--card-hover);
+}
+
+.settings-github-star-btn:focus-visible {
+  outline: none;
+  box-shadow: var(--focus-ring-strong);
+  border-color: var(--todo);
+}
+
+.settings-github-star-btn__action {
+  display: inline-flex;
+  align-items: center;
+  gap: 5px;
+  padding: 4px 10px;
+}
+
+.settings-github-star-btn__count {
+  display: inline-flex;
+  align-items: center;
+  padding: 4px 9px;
+  border-left: var(--btn-border-width) solid var(--border);
+  background: color-mix(in srgb, var(--surface) 60%, var(--card));
+  color: var(--text-muted);
+  font-variant-numeric: tabular-nums;
+}
+
 /* === Settings Modal: sizing + resizability === */
 .settings-modal {
   width: min(95vw, 1100px);