chore: hapus fitur materi (learning materials + RAG chat)

Hapus fitur materi seluruhnya dari GMW monorepo:

Backend:
- Hapus module materi/ (index.ts, materi.repository.ts, materi.schema.ts,
  materi.service.ts, ragClient.ts)
- Hapus materiRouter dari orpc/router.ts (imports, const, appRouter entry)
- Hapus pgMateriDocumentsTable + types dari shared/database/schema.ts

Frontend:
- Hapus route pages app/(dashboard)/materi/ (page, [id], chat, new)
- Hapus lib/api/materi.ts (oRPC client wrappers)
- Hapus lib/types/materi.ts + export dari index.ts
- Hapus nav item "Materi" dari lib/navigation.ts + unused BookOpen import

Scripts:
- Hapus scripts/add-materi-documents.sql
- Tambah scripts/drop-materi-documents.sql (ops DB cleanup)

Verification:
- Backend: npx tsc --noEmit — clean (exit 0)
- Frontend: npx tsc --noEmit — clean (exit 0)
- Grep: zero materi code references remaining (hanya di drop-materi-documents.sql)

RAG dependencies (messages/embed.ts, messages/qdrant.ts) tetap karena juga
dipakai oleh messages.service.ts.

services/backend/src/orpc/router.ts

@@ -3,16 +3,8 @@ import { z } from "zod";
 import { analysisService } from "../modules/analysis/analysis.service";
 import { chatRequestSchema } from "../modules/chatbot/chatbot.schema";
 import { chatbotService } from "../modules/chatbot/chatbot.service";
-// ── Service imports ──────────────────────────────────────────────
 import { dashboardService } from "../modules/dashboard/dashboard.service";
 import { knowledgeService } from "../modules/knowledge/knowledge.service";
-import {
-  createMateriSchema,
-  materiQuerySchema,
-  materiRagChatSchema,
-  materiService,
-  updateMateriSchema,
-} from "../modules/materi/index.js";
 import {
   mediaLoopSchema,
   mediaQueueSchema,
@@ -434,28 +426,6 @@ const uiStateRouter = {
     .handler(({ input }) => uiStateService.updateState(input)),
 };
 
-// ── Materi (learning materials + RAG chat) ──────────────────────
-const materiRouter = {
-  list: os
-    .input(materiQuerySchema)
-    .handler(({ input }) => materiService.list(input)),
-  detail: os
-    .input(z.object({ id: z.string() }))
-    .handler(({ input }) => materiService.byId(input.id)),
-  create: os
-    .input(createMateriSchema)
-    .handler(({ input }) => materiService.create(input, "anonymous")),
-  update: os
-    .input(z.object({ id: z.string() }).merge(updateMateriSchema))
-    .handler(({ input }) => materiService.update(input.id, input)),
-  delete: os
-    .input(z.object({ id: z.string() }))
-    .handler(({ input }) => materiService.delete(input.id)),
-  chat: os
-    .input(materiRagChatSchema)
-    .handler(({ input }) => materiService.ragChat(input, "anonymous")),
-};
-
 // ── Root router ───────────────────────────────────────────────────
 export const appRouter = {
   dashboard: dashboardRouter,
@@ -469,7 +439,6 @@ export const appRouter = {
   config: configRouter,
   uiState: uiStateRouter,
   knowledge: knowledgeRouter,
-  materi: materiRouter,
 };
 
 export type AppRouter = typeof appRouter;