feat(gui): Run Diagnostic flow on the Games page — 0.12.0

Brings the guided diagnostic (0.11.0 core/CLI) into the GUI:
- Each game row gets a "Run Diagnostic" button → starts a focused, game-tagged
  capture and shows a recording banner (live sample count + GPU-lost indicator)
  with Finish & analyze / Discard.
- Finishing runs core.diagnostic.finish() off the UI thread and opens a results
  dialog (gui/diagnostic_dialog.py): window-scoped capture summary + findings
  cards (reusing render_summary + finding_card).
- Banner restores on showEvent if a capture is still running (navigate away/back).

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

docs/ROADMAP.md

@@ -41,10 +41,12 @@ Ubuntu + NVIDIA first; `.deb` distribution (see `DECISIONS.md`).
 - [ ] M11 tray / menu-bar applet (QSystemTrayIcon: live M1 readouts + Run Diagnostic +
       supporting actions — D13)
 - [~] Guided diagnostic session (pick game → focused M3 capture → M4 scan → findings),
-      shared by tray/GUI/CLI — *core + CLI done* (`core/diagnostic.py`, `rigdoctor diagnose
-      start/status/finish`): tags a focused capture with the chosen game (own diagnostic log,
-      window-scoped report) and combines the capture summary with the M4 findings. *Pending:*
-      the GUI/tray "Run Diagnostic" button, and auto start/stop via the D12 wrapper/watcher.
+      shared by tray/GUI/CLI — *core + CLI + GUI done* (`core/diagnostic.py`, `rigdoctor
+      diagnose start/status/finish`, and a **Run Diagnostic** button per game on the GUI Games
+      page → recording banner → results dialog with the capture summary + findings). Tags a
+      focused capture with the chosen game (own diagnostic log, window-scoped report) and
+      combines the capture summary with the M4 findings. *Pending:* the tray (M11) entry point,
+      and auto start/stop via the D12 wrapper/watcher.
 - [ ] Logger trigger modes: always-on + game-launch (D12 — wrapper first:
       `rigdoctor wrap %command%` + global Steam compat-tool; zero-config watcher
       (Steam RunningAppID + /proc) and GameMode hook follow)