fix: remove pgvector dependency from AI knowledge retrieval

modules/core/server/schema.ts

@@ -11,7 +11,6 @@ import {
   timestamp,
   uniqueIndex,
   uuid,
-  vector,
 } from "drizzle-orm/pg-core";
 
 export const accountStatusEnum = pgEnum("account_status", ["active", "disabled", "pending"]);
@@ -555,7 +554,7 @@ export const aiKnowledgeChunks = pgTable("ai_knowledge_chunks", {
   scope: aiKnowledgeScopeEnum("scope").notNull(),
   chunkIndex: integer("chunk_index").notNull(),
   content: text("content").notNull(),
-  embedding: vector("embedding", { dimensions: AI_KNOWLEDGE_EMBEDDING_DIMENSIONS }).notNull(),
+  embedding: jsonb("embedding").$type<number[]>().notNull().default(sql`'[]'::jsonb`),
   sourceTitle: text("source_title").notNull(),
   sourceCategory: text("source_category").notNull().default(""),
   createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),