Rebalance overlay layout and fix the layout-on-launch overlap

Feedback from real use: the center column was far too wide and Injection/Log too
narrow; Audio was too tall while Controllers/Video were too short; and the layout
overlapped on launch until "Reset layout" was pressed.

- Columns are now proportional: Injection (left) and Log (right) take 36% each of the
  usable width, the center control column 28% -- so the wide panels are wide and the
  control panels narrow.
- The center stack heights are evened out (Controllers 30% / Video 38% / Audio 32% of
  the column), so Audio no longer hogs it.
- The default layout is now forced (ImGuiCond_Always) for the first few frames after
  launch, because the viewport WorkSize isn't trustworthy on frame 0 -- FirstUseEver
  was locking in those wrong (overlapping) positions until a manual Reset layout.

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

host/src/ui/app_chrome.cpp

@@ -13,6 +13,10 @@ namespace
 // Set by "View -> Reset layout"; true for the one frame in which panels re-apply
 // their default position/size, then cleared by apply_layout_end_frame().
 bool g_layout_reset = false;
+// Force the computed layout for the first few frames after launch: the viewport
+// WorkSize isn't trustworthy on frame 0, and FirstUseEver would otherwise lock in
+// those wrong positions (overlapping) until the user pressed Reset layout.
+int g_startup_force = 4;
 } // namespace
 
 void request_layout_reset()
@@ -23,6 +27,10 @@ void request_layout_reset()
 void apply_layout_end_frame()
 {
 	g_layout_reset = false;
+	if (g_startup_force > 0)
+	{
+		--g_startup_force;
+	}
 }
 
 void apply_panel_layout(Panel panel)
@@ -33,43 +41,52 @@ void apply_panel_layout(Panel panel)
 	const float m = 12.0f;   // outer margin
 	const float gap = 10.0f; // between panels
 
-	const float left_w = 440.0f;  // Injection (window list + hook diagnostics)
-	const float right_w = 380.0f; // Log
-	const float center_x = o.x + m + left_w + gap;
-	const float right_x = o.x + s.x - right_w - m;
-	const float center_w = std::max(360.0f, right_x - gap - center_x);
+	// Three columns: Injection (left) and Log (right) are the wide ones (window list
+	// titles / log lines); the center control-panel column is the narrow one.
+	const float usable_w = std::max(600.0f, s.x - 2.0f * m - 2.0f * gap);
+	const float left_w = usable_w * 0.36f;
+	const float center_w = usable_w * 0.28f;
+	const float right_w = usable_w * 0.36f;
+	const float left_x = o.x + m;
+	const float center_x = left_x + left_w + gap;
+	const float right_x = center_x + center_w + gap;
+
+	const float top = o.y + m;
 	const float full_h = std::max(200.0f, s.y - 2.0f * m);
-	const float ctrl_h = 210.0f; // Controllers
-	const float vid_h = 250.0f;  // Video mirror
-	const float audio_y = o.y + m + ctrl_h + gap + vid_h + gap;
-	const float bottom = o.y + m + full_h;
+
+	// Center column stacks Controllers / Video / Audio at roughly even heights (Video
+	// a touch taller for its graphs), so Audio no longer hogs the column.
+	const float stack_avail = std::max(150.0f, full_h - 2.0f * gap);
+	const float ctrl_h = stack_avail * 0.30f;
+	const float vid_h = stack_avail * 0.38f;
+	const float audio_h = stack_avail * 0.32f;
 
 	ImVec2 pos, size;
 	switch (panel)
 	{
 	case Panel::Injection:
-		pos = ImVec2(o.x + m, o.y + m);
+		pos = ImVec2(left_x, top);
 		size = ImVec2(left_w, full_h);
 		break;
 	case Panel::Controllers:
-		pos = ImVec2(center_x, o.y + m);
+		pos = ImVec2(center_x, top);
 		size = ImVec2(center_w, ctrl_h);
 		break;
 	case Panel::Video:
-		pos = ImVec2(center_x, o.y + m + ctrl_h + gap);
+		pos = ImVec2(center_x, top + ctrl_h + gap);
 		size = ImVec2(center_w, vid_h);
 		break;
 	case Panel::Audio:
-		pos = ImVec2(center_x, audio_y);
-		size = ImVec2(center_w, std::max(180.0f, bottom - audio_y));
+		pos = ImVec2(center_x, top + ctrl_h + gap + vid_h + gap);
+		size = ImVec2(center_w, audio_h);
 		break;
 	case Panel::Log:
-		pos = ImVec2(right_x, o.y + m);
+		pos = ImVec2(right_x, top);
 		size = ImVec2(right_w, full_h);
 		break;
 	}
 
-	const ImGuiCond cond = g_layout_reset ? ImGuiCond_Always : ImGuiCond_FirstUseEver;
+	const ImGuiCond cond = (g_layout_reset || g_startup_force > 0) ? ImGuiCond_Always : ImGuiCond_FirstUseEver;
 	ImGui::SetNextWindowPos(pos, cond);
 	ImGui::SetNextWindowSize(size, cond);
 }