feat(search): filter tag results by colour

Pass the active colour filter through tag searches and apply the existing palette match inside the tag query and count paths.

Update the UI Lab mock backend so colour filtering behaves the same way when testing tag search results.

src/dev/mockBackend.ts

@@ -9,6 +9,36 @@ let nextAlbumId = 100;
 let nextTagId = 10_000;
 
 type AnyPayload = Record<string, any> | undefined;
+type Rgb = [number, number, number];
+
+const mockPalette: Rgb[] = [
+  [59, 125, 216],
+  [31, 182, 166],
+  [76, 175, 80],
+  [242, 207, 46],
+  [232, 134, 46],
+  [226, 59, 59],
+  [139, 92, 246],
+  [236, 72, 153],
+  [139, 90, 43],
+  [26, 26, 26],
+  [245, 245, 245],
+  [154, 160, 166],
+];
+
+function isRgb(value: unknown): value is Rgb {
+  return Array.isArray(value) && value.length === 3 && value.every((entry) => typeof entry === "number");
+}
+
+function colorDistanceSq(left: Rgb, right: Rgb): number {
+  return (left[0] - right[0]) ** 2 + (left[1] - right[1]) ** 2 + (left[2] - right[2]) ** 2;
+}
+
+function matchesMockColor(image: ImageRecord, color: Rgb): boolean {
+  const primary = mockPalette[(image.id - 1) % mockPalette.length];
+  const secondary = mockPalette[(image.folder_id + image.rating) % mockPalette.length];
+  return colorDistanceSq(primary, color) <= 4_900 || colorDistanceSq(secondary, color) <= 4_900;
+}
 
 function params(payload: unknown): Record<string, any> {
   if (!payload || typeof payload !== "object") return {};
@@ -28,6 +58,7 @@ function page<T>(items: T[], offset = 0, limit = 200) {
 function filterImages(input: ImageRecord[], payload: unknown): ImageRecord[] {
   const p = params(payload);
   const query = String(p.search ?? p.query ?? "").trim().toLowerCase();
+  const color = isRgb(p.color) ? p.color : null;
   return input.filter((image) => {
     if (p.folder_id !== undefined && p.folder_id !== null && image.folder_id !== p.folder_id) return false;
     if (p.media_kind && image.media_kind !== p.media_kind) return false;
@@ -36,6 +67,7 @@ function filterImages(input: ImageRecord[], payload: unknown): ImageRecord[] {
     if (p.embedding_failed_only && image.embedding_status !== "failed") return false;
     if (p.tagging_failed_only && !image.ai_tagger_error) return false;
     if (query && !image.filename.toLowerCase().includes(query)) return false;
+    if (color && !matchesMockColor(image, color)) return false;
     return true;
   });
 }