Add search functionality for vocabulary in VocabController and VocabService

- Implemented a new searchVocabs method in VocabService to allow users to search for vocabulary based on learning and mother tongue terms.
- Updated VocabController to include the searchVocabs method wrapped with user authentication.
- Added a new route in vocabRouter for searching vocabulary by language ID.
- Enhanced VocabChapterView and VocabLanguageView components to include a button for opening the search dialog.
- Added translations for search-related terms in both German and English locales, improving user accessibility.

backend/services/vocabService.js

@@ -408,6 +408,52 @@ export default class VocabService {
     return { languageId: access.id, isOwner: access.isOwner, vocabs: rows };
   }
 
+  async searchVocabs(hashedUserId, languageId, { learning = '', motherTongue = '' } = {}) {
+    const user = await this._getUserByHashedId(hashedUserId);
+    const access = await this._getLanguageAccess(user.id, languageId);
+
+    const learningTerm = typeof learning === 'string' ? learning.trim() : '';
+    const motherTerm = typeof motherTongue === 'string' ? motherTongue.trim() : '';
+    if (!learningTerm && !motherTerm) {
+      const err = new Error('Missing search term');
+      err.status = 400;
+      throw err;
+    }
+
+    const learningLike = learningTerm ? `%${learningTerm}%` : null;
+    const motherLike = motherTerm ? `%${motherTerm}%` : null;
+
+    const rows = await sequelize.query(
+      `
+      SELECT
+        cl.id,
+        c.id AS "chapterId",
+        c.title AS "chapterTitle",
+        l1.text AS "learning",
+        l2.text AS "motherTongue"
+      FROM community.vocab_chapter_lexeme cl
+      JOIN community.vocab_chapter c ON c.id = cl.chapter_id
+      JOIN community.vocab_lexeme l1 ON l1.id = cl.learning_lexeme_id
+      JOIN community.vocab_lexeme l2 ON l2.id = cl.reference_lexeme_id
+      WHERE c.language_id = :languageId
+        AND (:learningLike IS NULL OR l1.text ILIKE :learningLike)
+        AND (:motherLike IS NULL OR l2.text ILIKE :motherLike)
+      ORDER BY l2.text ASC, l1.text ASC, c.title ASC
+      LIMIT 200
+      `,
+      {
+        replacements: {
+          languageId: access.id,
+          learningLike,
+          motherLike,
+        },
+        type: sequelize.QueryTypes.SELECT,
+      }
+    );
+
+    return { languageId: access.id, results: rows };
+  }
+
   async addVocabToChapter(hashedUserId, chapterId, { learning, reference }) {
     const user = await this._getUserByHashedId(hashedUserId);
     const ch = await this._getChapterAccess(user.id, chapterId);