Revert "fix: switch embedding dimension from 1536 to 2560 for qwen-embedding-4b"

This reverts commit e09ea3a145.

memento-note/tests/ai-provider.spec.ts

@@ -47,7 +47,7 @@ test.describe('AI Provider Configuration Tests', () => {
 
     // Verify embeddings provider is working
     expect(result.embeddingsProvider).toBe('openai');
-    expect(result.embeddingLength).toBe(2560); // OpenAI text-embedding-3-small
+    expect(result.embeddingLength).toBe(1536); // OpenAI text-embedding-3-small
     expect(result.details?.provider).toBe('OpenAI');
   });
 

memento-note/tests/migration/integrity.test.ts

@@ -232,7 +232,7 @@ describe('Data Integrity Tests', () => {
       const vecStr = '[0.1,0.2,0.3,0.4,0.5]'
       await prisma.$executeRawUnsafe(
         `INSERT INTO "NoteEmbedding" ("id", "noteId", "embedding", "createdAt", "updatedAt")
-         VALUES (gen_random_uuid(), $1, $2::vector(2560), now(), now())`,
+         VALUES (gen_random_uuid(), $1, $2::vector(1536), now(), now())`,
         note.id,
         vecStr
       )