feat(pokemon): decouple official data ID from display ID during fetch

Allow fetching data and images using official identifiers regardless of the custom display ID.
Extract data ID directly from image paths instead of relying on the display ID.
Only auto-fill display ID from fetched data if the field is currently empty.

backend/src/queries.ts

@@ -1520,13 +1520,28 @@ function pokemonImageLabel(image: PokemonImage | null | undefined): string {
   return image.source === 'upload' || isUploadImagePath(image.path) ? imagePathLabel(image.path) : `${image.style} - ${image.version} - ${image.variant}`;
 }
 
-function pokemonImageCandidateForPath(id: number, path: string): PokemonImage | null {
+function pokemonImageDataIdFromPath(path: string): number | null {
+  const match = path.match(/^\/sprites\/pokemon\/(?:.+\/)?([1-9]\d*)\.(?:png|gif|svg)$/);
+  if (!match) {
+    return null;
+  }
+
+  const id = Number(match[1]);
+  return Number.isSafeInteger(id) ? id : null;
+}
+
+function pokemonImageCandidateForPath(path: string): PokemonImage | null {
   const cleanPath = path.trim();
+  const id = pokemonImageDataIdFromPath(cleanPath);
+  if (!id) {
+    return null;
+  }
+
   const candidate = pokemonImageCandidates(id).find((item) => item.path === cleanPath);
   return candidate ? pokemonImageWithUrl(candidate) : null;
 }
 
-function cleanPokemonImage(value: unknown, pokemonId: number): PokemonImage | null {
+function cleanPokemonImage(value: unknown, displayId: number): PokemonImage | null {
   const path = typeof value === 'string' ? value.trim() : '';
   if (path === '') {
     return null;
@@ -1541,13 +1556,13 @@ function cleanPokemonImage(value: unknown, pokemonId: number): PokemonImage | nu
       url: uploadImageUrl(path),
       style: 'Upload',
       version: 'Community upload',
-      variant: `#${pokemonId}`,
+      variant: `#${displayId}`,
       description: '',
       source: 'upload'
     };
   }
 
-  const image = pokemonImageCandidateForPath(pokemonId, path);
+  const image = pokemonImageCandidateForPath(path);
   if (!image) {
     throw validationError('server.validation.pokemonImagePathInvalid');
   }