refactor(settings): simplify GC aggressiveness to Off/Light only

Remove Moderate, Heavy, and Extreme GC aggressiveness levels, keeping only Off and Light options for simpler configuration.

- Light mode now uses 75%/90% VRAM thresholds

- Simplified switch statements in texture/buffer cache

- Updated UI dropdowns for desktop and Android

- Light is now the default and recommended setting

src/common/settings.h

@@ -520,9 +520,9 @@ struct Values {
 
     // GC aggressiveness level for texture/buffer cache eviction
     SwitchableSetting<GCAggressiveness, true> gc_aggressiveness{linkage,
-                                                                 GCAggressiveness::Moderate,
+                                                                 GCAggressiveness::Light,
                                                                  GCAggressiveness::Off,
-                                                                 GCAggressiveness::Extreme,
+                                                                 GCAggressiveness::Light,
                                                                  "gc_aggressiveness",
                                                                  Category::RendererAdvanced,
                                                                  Specialization::Default,

src/common/settings_enums.h

@@ -878,11 +878,8 @@ inline u32 EnumMetadata<ExtendedDynamicState>::Index() {
 
 // FIXED: VRAM leak prevention - GC aggressiveness levels
 enum class GCAggressiveness : u32 {
-    Off = 0,        // Disable automatic GC (not recommended)
-    Light = 1,      // Light GC - only evict very old textures
-    Moderate = 2,   // Moderate GC - balanced eviction (default)
-    Heavy = 3,      // Heavy GC - aggressive eviction for low VRAM systems
-    Extreme = 4,    // Extreme GC - maximum eviction for 4GB VRAM systems
+    Off = 0,    // Disable automatic GC (not recommended)
+    Light = 1,  // Light GC - gentle eviction of old textures/buffers
 };
 
 template <>
@@ -891,9 +888,6 @@ EnumMetadata<GCAggressiveness>::Canonicalizations() {
     return {
         {"Off", GCAggressiveness::Off},
         {"Light", GCAggressiveness::Light},
-        {"Moderate", GCAggressiveness::Moderate},
-        {"Heavy", GCAggressiveness::Heavy},
-        {"Extreme", GCAggressiveness::Extreme},
     };
 }