feat: SOTA image enhancement with one-click auto-improve (#55)

* feat(image-enhancement): add analysis and correction types

* feat(image-enhancement): implement auto-enhance analysis and correction engine

* test(image-enhancement): add unit tests for auto-enhance engine

* feat(image-enhancement): add API route with analyze endpoint and register in constants/i18n

* feat(image-enhancement): add UI component with mode selector, intensity slider, and analysis badges

* test(image-enhancement): add integration and e2e tests

* fix(image-enhancement): use modulate instead of gamma for exposure correction

Sharp's gamma() only accepts values between 1.0 and 3.0, but brightening
underexposed images computed gamma < 1.0. Switch to modulate({ brightness })
which handles both brightening and darkening correctly.

---------

Co-authored-by: stirling-image <stirling-image@users.noreply.github.com>

apps/web/src/lib/tool-registry.tsx

@@ -234,6 +234,11 @@ const SmartCropSettings = lazy(() =>
     default: m.SmartCropSettings,
   })),
 );
+const ImageEnhancementSettings = lazy(() =>
+  import("@/components/tools/image-enhancement-settings").then((m) => ({
+    default: m.ImageEnhancementSettings,
+  })),
+);
 
 // ── Color tool wrapper ─────────────────────────────────────────────
 // Color tools share a single component but differ by toolId.
@@ -351,6 +356,14 @@ export const toolRegistry = new Map<string, ToolRegistryEntry>([
     },
   ],
   ["smart-crop", { displayMode: "before-after", Settings: SmartCropSettings }],
+  [
+    "image-enhancement",
+    {
+      displayMode: "live-preview" as DisplayMode,
+      livePreview: true,
+      Settings: ImageEnhancementSettings as never,
+    },
+  ],
 ]);
 
 export function getToolRegistryEntry(toolId: string): ToolRegistryEntry | undefined {