feat: SOTA sharpening tool with 3 methods and 7 presets (#56)

* feat(sharpening): add SharpenAdvancedOptions type for multi-method sharpening

* feat(sharpening): implement 3-method sharpen engine (adaptive, USM, high-pass)

* feat(sharpening): add dedicated API route with Zod validation

* feat(sharpening): register tool in constants, i18n, and suggested tools

* feat(sharpening): add settings UI with presets, methods, and advanced controls

* feat(sharpening): register tool in frontend registry with before-after display

---------

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

packages/image-engine/src/operations/sharpen.ts

@@ -1,4 +1,4 @@
-import type { Sharp, SharpenOptions } from "../types.js";
+import type { Sharp, SharpenAdvancedOptions, SharpenOptions } from "../types.js";
 
 export async function sharpen(image: Sharp, options: SharpenOptions): Promise<Sharp> {
   const { value } = options;
@@ -13,3 +13,95 @@ export async function sharpen(image: Sharp, options: SharpenOptions): Promise<Sh
 
   return image.sharpen({ sigma });
 }
+
+const DENOISE_KERNEL: Record<string, number> = {
+  light: 3,
+  medium: 5,
+  strong: 7,
+};
+
+export async function sharpenAdvanced(
+  image: Sharp,
+  options: SharpenAdvancedOptions,
+): Promise<Sharp> {
+  const { method, denoise } = options;
+
+  // Optional noise reduction pre-pass
+  if (denoise && denoise !== "off") {
+    const kernelSize = DENOISE_KERNEL[denoise];
+    if (kernelSize) {
+      image = image.median(kernelSize);
+    }
+  }
+
+  switch (method) {
+    case "adaptive":
+      return sharpenAdaptive(image, options);
+    case "unsharp-mask":
+      return sharpenUnsharpMask(image, options);
+    case "high-pass":
+      return sharpenHighPass(image, options);
+    default:
+      throw new Error(`Unknown sharpening method: ${method}`);
+  }
+}
+
+function sharpenAdaptive(image: Sharp, options: SharpenAdvancedOptions): Sharp {
+  const sigma = options.sigma ?? 1.0;
+  const m1 = options.m1 ?? 1.0;
+  const m2 = options.m2 ?? 3.0;
+  const x1 = options.x1 ?? 2.0;
+  const y2 = options.y2 ?? 12;
+  const y3 = options.y3 ?? 20;
+  return image.sharpen({ sigma, m1, m2, x1, y2, y3 });
+}
+
+function sharpenUnsharpMask(image: Sharp, options: SharpenAdvancedOptions): Sharp {
+  const amount = options.amount ?? 100;
+  const radius = options.radius ?? 1.0;
+  const threshold = options.threshold ?? 0;
+  const sigma = radius;
+  const intensity = amount / 100;
+  const x1 = (threshold / 255) * 10;
+  return image.sharpen({ sigma, m1: intensity, m2: intensity, x1, y2: 15, y3: 25 });
+}
+
+function sharpenHighPass(image: Sharp, options: SharpenAdvancedOptions): Sharp {
+  const strength = options.strength ?? 50;
+  const kernelSize = options.kernelSize ?? 3;
+  const s = strength / 100;
+
+  if (kernelSize === 5) {
+    const k = [
+      0,
+      -s,
+      -s,
+      -s,
+      0,
+      -s,
+      s,
+      s * 2,
+      s,
+      -s,
+      -s,
+      s * 2,
+      1 + s * 8,
+      s * 2,
+      -s,
+      -s,
+      s,
+      s * 2,
+      s,
+      -s,
+      0,
+      -s,
+      -s,
+      -s,
+      0,
+    ];
+    return image.convolve({ width: 5, height: 5, kernel: k });
+  }
+
+  const k = [0, -s, 0, -s, 1 + 4 * s, -s, 0, -s, 0];
+  return image.convolve({ width: 3, height: 3, kernel: k });
+}