Phase 4 Stage 10 Maestro: 09_chat_tab.yaml + seed-pending-payment endpoint

Closes the Stage 10 acceptance criterion §10.11 #13 (Maestro coverage).

- New dev-only `POST /internal/_test/seed-pending-payment` — inserts a
  payment_sessions row in `pending` status with expires_at 20m out, so
  the Pembayaran sub-tab has a deterministic row to render. Body
  accepts { phone, isExtension?, amount?, durationMinutes?, mode? }.
  Gated on NODE_ENV != 'production' like the other test routes.

- New Maestro helper script `seed_pending_payment.js` mirrors the
  existing seed_history_session pattern.

- New flow `09_chat_tab.yaml`:
    cold-start onboarding → home (returning view) →
    seed completed session + seed pending payment →
    tap "💬 chat" bottom-nav → lands on /chat/aktif via redirect →
    assert "aktif" / "pembayaran" / "selesai" pills + empty-state copy →
    tap pembayaran → assert "menunggu pembayaran sesi" + "bayar Rp..." →
    tap selesai → assert "X menit" duration row → tap row → assert
    "Transkrip Chat" appbar → back → still on /chat/selesai.

  Maestro parsed the YAML cleanly and started executing against the
  device; full run requires backend + online mitra in dev DB (same
  pre-reqs as flows 03/05/06/08).

- TECH_DEBT entry: Stage 10 retired the standalone bestie-history list
  screen, which means (a) the "curhat lagi" targeted-payment entry
  point has no UI affordance anywhere in the app — its plumbing in
  payment_notifier / payment_screen is now orphaned, and (b) the
  Stage 8 flow `08_returning_targeted.yaml` will fail at
  `assertVisible: "Riwayat Chat"` because it expects the deleted
  screen. Three fix paths listed in the entry for product to pick.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/src/routes/internal/_test.routes.js

@@ -245,4 +245,45 @@ export const internalTestRoutes = async (fastify) => {
     `
     return { ok: true, session_id: session.id, mitra_id: mitra.id, mitra_name: mitra.display_name }
   })
+
+  // Seed a payment_sessions row in `pending` status for the customer linked
+  // to `phone`, with expires_at safely in the future. Used by Maestro Stage
+  // 10 flow (09_chat_tab.yaml) to populate the Pembayaran sub-tab without
+  // walking the multi-screen S6 paywall → method → duration → method flow.
+  //
+  // Body: { phone, isExtension?, amount?, durationMinutes?, mode? }
+  //   - isExtension: defaults false (initial-session payment)
+  //   - amount: defaults 5000 IDR
+  //   - durationMinutes: defaults 15
+  //   - mode: 'chat' (default) | 'call'
+  fastify.post('/seed-pending-payment', async (request, reply) => {
+    const phone = request.body?.phone
+    if (!phone) {
+      return reply.code(400).send({ error: 'phone required in body' })
+    }
+    const isExtension = request.body?.isExtension === true
+    const amount = Number.isFinite(request.body?.amount) ? request.body.amount : 5000
+    const durationMinutes = Number.isFinite(request.body?.durationMinutes)
+      ? request.body.durationMinutes
+      : 15
+    const mode = request.body?.mode === 'call' ? 'call' : 'chat'
+
+    const [customer] = await sql`
+      SELECT id FROM customers WHERE phone = ${phone} LIMIT 1
+    `
+    if (!customer) {
+      return reply.code(404).send({ error: 'no_customer_for_phone', phone })
+    }
+    const [row] = await sql`
+      INSERT INTO payment_sessions (
+        customer_id, amount, duration_minutes, is_first_session_discount,
+        is_extension, status, mode, expires_at
+      ) VALUES (
+        ${customer.id}, ${amount}, ${durationMinutes}, false,
+        ${isExtension}, 'pending', ${mode}, NOW() + INTERVAL '20 minutes'
+      )
+      RETURNING id, customer_id, amount, is_extension, status, expires_at
+    `
+    return { ok: true, payment_id: row.id, ...row }
+  })
 }