Turn Instruction into a chat with an agent that asks

The Instruction page is now a conversation with the Express Agent. Each
message updates the draft plan, and when something is unclear (a part it
did not understand, a video count with no cadence, a schedule over 50 per
week, weekly research with no day, a missing topic) the agent asks right
in the chat, one question at a time, with replies to pick or type. Once
the plan is clear it offers to start the schedules and reports the result
in the chat. The plan stays editable beside the chat.

The chat text is also larger and darker than the mockup's 9-11px grey.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -16,6 +16,7 @@ npm test           # tes parser, jadwal, SCORM, dan ekspor (Vitest)
 - Clerk key dibaca dari `VITE_CLERK_PUBLISHABLE_KEY`, atau otomatis dari `../learning-lab/backend/.env`.
 - Tombol "Open in Learning Studio" di Results membuka `VITE_STUDIO_URL` (default `http://localhost:5173`).
 - Dua bahasa: English (default) dan Indonesia, lewat tombol EN/ID di topbar dan halaman login. Teks ada di `src/i18n.ts`; pilihan disimpan per perangkat.
+- Instruction berbentuk chat dengan agen (`src/express/agent.ts`): bila ada yang belum jelas (bagian yang tidak dipahami, frekuensi video, hari riset, topik), agen langsung bertanya di chat dengan opsi jawaban, lalu menawarkan untuk memulai jadwal. Pemahamannya tetap memakai parser deterministik, bukan LLM.
 - Login wajib memakai akun Clerk dengan organisasi aktif: agents, jadwal, dan kredit semuanya per organisasi.
 
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