fix(gui): limit Files & Media collapsible child height to reasonable max

The begin_child() was using (0, -40) which made it stretch to fill parent.
Changed to (0, min(len(items) * 30 + 50, 300)) so it:
- Sizes to content (30px per row + 50px header)
- Caps at 300px max height
- Allows scrolling when content overflows

config.toml

@@ -23,7 +23,7 @@ separate_tool_calls_panel = false
 bg_shader_enabled = false
 crt_filter_enabled = false
 separate_task_dag = false
-separate_usage_analytics = false
+separate_usage_analytics = true
 separate_tier1 = false
 separate_tier2 = false
 separate_tier3 = false
@@ -34,7 +34,7 @@ separate_external_tools = false
 "Project Settings" = true
 "Files & Media" = true
 "AI Settings" = true
-"MMA Dashboard" = true
+"MMA Dashboard" = false
 "Task DAG" = false
 "Usage Analytics" = true
 "Tier 1" = false
@@ -55,7 +55,7 @@ Theme = true
 Diagnostics = false
 "External Tools" = false
 "Shader Editor" = false
-"Undo/Redo History" = false
+"Undo/Redo History" = true
 
 [theme]
 palette = "Nord Dark"