Phase 3 scaffold: chat engine (WebSocket, FCM, pricing, timer, extension, history)

- Backend: WebSocket plugin, chat/pricing/timer/extension/closure/notification services
- Client app: ChatBloc, pricing dialog, chat screen with message status, extension/goodbye flow, history
- Mitra app: MitraChatBloc, ExtensionBloc, chat screen, extension accept/reject, history
- Control center: free trial, extension timeout, early end config toggles
- DB migration: chat_messages, session_closures, session_extensions, customer_transactions tables

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/src/services/config.service.js

@@ -29,3 +29,73 @@ export const setMaxCustomersPerMitra = async (value) => {
   `
   return { max_customers_per_mitra: value }
 }
+
+// --- Phase 3 config ---
+
+export const getFreeTrialConfig = async () => {
+  const [enabledRow] = await sql`SELECT value FROM app_config WHERE key = 'free_trial_enabled'`
+  const [durationRow] = await sql`SELECT value FROM app_config WHERE key = 'free_trial_duration_minutes'`
+  return {
+    enabled: enabledRow?.value?.value ?? false,
+    duration_minutes: durationRow?.value?.value ?? 5,
+  }
+}
+
+export const setFreeTrialConfig = async ({ enabled, duration_minutes }) => {
+  if (enabled !== undefined) {
+    await sql`
+      INSERT INTO app_config (key, value, updated_at)
+      VALUES ('free_trial_enabled', ${sql.json({ value: enabled })}, NOW())
+      ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()
+    `
+  }
+  if (duration_minutes !== undefined) {
+    await sql`
+      INSERT INTO app_config (key, value, updated_at)
+      VALUES ('free_trial_duration_minutes', ${sql.json({ value: duration_minutes })}, NOW())
+      ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()
+    `
+  }
+  return getFreeTrialConfig()
+}
+
+export const getExtensionTimeoutConfig = async () => {
+  const [row] = await sql`SELECT value FROM app_config WHERE key = 'extension_timeout_seconds'`
+  return { extension_timeout_seconds: row?.value?.value ?? 60 }
+}
+
+export const setExtensionTimeoutConfig = async (seconds) => {
+  await sql`
+    INSERT INTO app_config (key, value, updated_at)
+    VALUES ('extension_timeout_seconds', ${sql.json({ value: seconds })}, NOW())
+    ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()
+  `
+  return { extension_timeout_seconds: seconds }
+}
+
+export const getEarlyEndConfig = async () => {
+  const [mitraRow] = await sql`SELECT value FROM app_config WHERE key = 'early_end_mitra_enabled'`
+  const [customerRow] = await sql`SELECT value FROM app_config WHERE key = 'early_end_customer_enabled'`
+  return {
+    mitra_enabled: mitraRow?.value?.value ?? false,
+    customer_enabled: customerRow?.value?.value ?? false,
+  }
+}
+
+export const setEarlyEndConfig = async ({ mitra_enabled, customer_enabled }) => {
+  if (mitra_enabled !== undefined) {
+    await sql`
+      INSERT INTO app_config (key, value, updated_at)
+      VALUES ('early_end_mitra_enabled', ${sql.json({ value: mitra_enabled })}, NOW())
+      ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()
+    `
+  }
+  if (customer_enabled !== undefined) {
+    await sql`
+      INSERT INTO app_config (key, value, updated_at)
+      VALUES ('early_end_customer_enabled', ${sql.json({ value: customer_enabled })}, NOW())
+      ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()
+    `
+  }
+  return getEarlyEndConfig()
+}