feat: preserve pipe-delimited OR groups in tags DTO

Stop splitting tags on | so that OR-group tokens (e.g. cat|dog) are
forwarded intact to the Universal Booru Wrapper, which applies the
correct engine-specific OR syntax per booru engine.

Pipelines the change through the full stack:
  App → |  (user types 'cat OR dog')
  API  → ['cat|dog']  (kept as OR-group token)
  Wrapper → '{  ~ cat  ~ dog }' (Gelbooru) / '~cat ~dog' (Danbooru/e621)

Author: AlejandroAkbal

src/booru/dto/booru-queries.dto.spec.ts

@@ -12,22 +12,21 @@ describe('booruQueryValuesPostsDTO', () => {
       expect(dto.tags).toEqual(['panty_&_stocking_with_garterbelt'])
     })
 
-    it('should split pipe-separated tags and decode each one', () => {
+    it('should preserve pipe-separated OR-group tokens as a single element and decode each part', () => {
       const dto = plainToInstance(booruQueryValuesPostsDTO, {
         tags: 'panty_%26_stocking_with_garterbelt|rating%3Asafe'
       })
 
-      expect(dto.tags).toEqual(['panty_&_stocking_with_garterbelt', 'rating:safe'])
+      expect(dto.tags).toEqual(['panty_&_stocking_with_garterbelt|rating:safe'])
     })
 
-    it('should normalize array tag inputs and keep tag array shape', () => {
+    it('should normalize array tag inputs and keep OR-group tokens intact', () => {
       const dto = plainToInstance(booruQueryValuesPostsDTO, {
         tags: ['panty_%26_stocking_with_garterbelt|rating%3Asafe', 'score%3A%3E100']
       })
 
       expect(dto.tags).toEqual([
-        'panty_&_stocking_with_garterbelt',
-        'rating:safe',
+        'panty_&_stocking_with_garterbelt|rating:safe',
         'score:>100'
       ])
     })

src/booru/dto/booru-queries.dto.ts

@@ -188,7 +188,7 @@ export class booruQueryValuesPostsDTO extends booruQueriesDTO {
 
     return (Array.isArray(value) ? value : [value])
       .map((tag) => (typeof tag === 'string' ? tag : String(tag)))
-      .flatMap((tag) => tag.trim().split('|'))
+      .map((tag) => tag.trim())
       .map((tag) => {
         if (!/%[0-9A-Fa-f]{2}/.test(tag)) {
           return tag