docs: plan tray click via Fyne 2.7 SetSystemTrayWindow

Fyne 2.7.0 adds desktop.App.SetSystemTrayWindow, which shows the window
on left-click and unblocks the deferred Tray Interaction item. Record the
2.6.3 -> 2.7.x upgrade dependency and the concrete wiring in run.go.

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

docs/ROADMAP.md

@@ -24,13 +24,21 @@ Cleanup checklist:
 
 ## Tray Interaction
 
-Improve tray icon interaction after choosing a tray backend path.
+Improve tray icon interaction: click the tray icon to show and focus the main
+window.
 
-- Add double-click on the tray icon to show and focus the main window.
+- Unblocked by Fyne 2.7.0, which added `desktop.App.SetSystemTrayWindow(window)`.
-- Current Fyne 2.5.3 desktop tray API exposes menu and icon setup, but does not
+  On Windows, macOS, and most Linux it shows the associated window on left-click;
-  expose click or double-click callbacks for the tray icon itself.
+  any tray menu then moves to right-click. There is still no raw click /
-- Revisit when Fyne exposes this callback, or evaluate a small platform-specific
+  double-click callback, so the behavior is single left-click (the conventional
-  tray integration if the behavior becomes important enough.
+  tray gesture), not the double-click originally sketched here.
+- The project is currently on Fyne 2.6.3, so this depends on a Fyne 2.6.3 -> 2.7.x
+  upgrade first (minor bump; re-verify the CGO build under MSYS2 UCRT64 and check
+  for 2.7 breaking changes). Track the upgrade as its own task.
+- After upgrading, the change in `src/ui/run.go` (configureSystemTray) is small:
+  call `desk.SetSystemTrayWindow(w)` alongside `SetSystemTrayMenu(menu)`. Keep the
+  existing "Show" menu item, which the Fyne docs recommend for less-compliant
+  Linux systems.
 
 ## Delivery And Packaging