fix(ui): commit FramebufferResize + ResetPanelLayout — orphaned during earlier cwd/sed shenanigans

These changes were referenced by commits fc1e193 / 6273255 / 2818fcc /
df9f2fd in their messages but the actual edits sat uncommitted in the
working tree — caught by the pre-merge code review pass. Without this
commit the merge to main would lose all the panel-layout fixes the
user already live-verified.

What was orphaned:

 · _window.FramebufferResize += OnFramebufferResize  (Run() wiring)
 · OnFramebufferResize handler — updates GL viewport + camera aspect
   on window resize; force-resets panel layout via ResetPanelLayout.
 · ResetPanelLayout(ImGuiCond) — positions Vitals / Chat / Debug /
   Settings panels at sensible defaults relative to current window
   size. Called at startup with FirstUseEver (imgui.ini wins on later
   launches) and on FramebufferResize / View menu item with Always
   (force reset).
 · View → "Reset window layout" menu item.
 · OnLoad seeding ResetPanelLayout(FirstUseEver) after panel
   registration so first-launch users don't see all panels stacked
   at (0,0).
 · DisplaySettings.Default.Resolution: "1920x1080" → "1280x720" so
   the default matches the WindowOptions startup size — opening
   Display + Save without edits is a complete visual no-op (the
   alternative would have triggered an immediate resize on every
   first-time Save).

dotnet build green; tests unaffected.

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

src/AcDream.UI.Abstractions/Panels/Settings/DisplaySettings.cs

@@ -23,11 +23,14 @@ public sealed record DisplaySettings(
     bool ShowFps)
 {
     /// <summary>Values used on first launch / when settings.json is absent.
-    /// FieldOfView (60°) and VSync (false) match the camera + window
-    /// defaults that shipped before L.0, so opening Display + Save
-    /// without touching anything is a visual no-op.</summary>
+    /// All defaults pinned to the pre-L.0 runtime state — Resolution
+    /// matches the WindowOptions startup size (1280×720), FieldOfView
+    /// matches camera FovY (60°), VSync matches WindowOptions (false),
+    /// ShowFps preserves the perf string in the title bar. Net effect:
+    /// opening Display + Save without touching anything is a complete
+    /// visual no-op.</summary>
     public static DisplaySettings Default { get; } = new(
-        Resolution:   "1920x1080",
+        Resolution:   "1280x720",
         Fullscreen:   false,
         VSync:        false,
         FieldOfView:  60f,