feat(integration): prepaid billing, engine UI, credits console, direct tasks, v2 final

- Prepaid credit system: org wallet, debit on usage, chat gate, admin credit console
- Engine UI: /manager, /tasks, /tasks/[id], /workforce, /dashboard, /traces pages
- Direct task creation (HTTP POST /tasks, MCP tasks_create) at pending_manager_review
- Pause/resume/cancel/answer actions in engine API and UI
- Employee cap (7 per org default), review pipeline guard (active reviewer required)
- Scheduler: wide window prevents org starvation; archived employees excluded from cap
- Tenant isolation: project-id cross-org 404, engine never uses another tenant's sandbox
- Order route fix: manager built with pipeline states + employee profiles
- Contract extension: ModelGrantPort.get_org_policy with DefaultOrgPolicy
- Engine event types in @agy/contracts (task.step, task.gate, run.log, run.tool, team.changed)
- api-engine.ts typed client; api-credit.ts client
- Alembic migration c4d5e6f7a8b9: prepaid credit + engine UI tables
- 859 tests passed, 1 skipped; ruff/mypy/tsc/eslint/vitest all green

Refs: PLAN-v2.md §9 (T1–T43), todo-v2-final.md

apps/api/app/application/engine/manager.py

@@ -88,6 +88,7 @@ from app.infrastructure.repositories.ai_control import (
     RateCardRepository,
 )
 from app.infrastructure.repositories.audit import UsageLedgerRepository
+from app.infrastructure.repositories.billing import CreditWalletRepository
 from app.infrastructure.repositories.engine import (
     EmployeeProfileRepository,
     PipelineStateRepository,
@@ -109,6 +110,11 @@ CHAT_MAX_ATTEMPTS = 2
 #: The message a new organization sees when the owner has granted nothing yet.
 NO_MODEL_GRANTED_MESSAGE = "منتظر تخصیص مدل توسط مالک سامانه"
 
+#: The reply a zero-credit organization gets instead of a model call (prepaid, D-B).
+CHAT_NO_CREDIT_MESSAGE = (
+    "اعتبار سازمان صفر است؛ مدیر پس از افزودن اعتبار توسط مالک سامانه پاسخ می‌دهد."
+)
+
 #: Bootstrap tiers per role, in the plan's order (strongest / balanced / fast).
 BOOTSTRAP_TIERS: dict[RoleKey, str] = {
     RoleKey.MANAGER: "strong",
@@ -223,6 +229,7 @@ class ManagerTurns:
         states: PipelineStateRepository | None = None,
         runner: TurnRunner | None = None,
         feed=None,
+        wallets: CreditWalletRepository | None = None,
     ) -> None:
         self.provider = provider
         self.employees = employees
@@ -239,6 +246,7 @@ class ManagerTurns:
         self.states = states
         self.runner = runner
         self.feed = feed
+        self.wallets = wallets
 
     # ------------------------------------------------------------------ #
     # 3.6 bootstrap                                                       #
@@ -404,6 +412,17 @@ class ManagerTurns:
         user_message = await self.messages.create(
             Message(thread_id=thread.id, role=MessageRole.USER, content=content)
         )
+        # Prepaid: a reply costs a model call, so an org with no credit gets the
+        # note instead. No model is called and no tag is executed.
+        if await self._out_of_credit(organization_id):
+            note = await self.messages.create(
+                Message(
+                    thread_id=thread.id,
+                    role=MessageRole.ASSISTANT,
+                    content=CHAT_NO_CREDIT_MESSAGE,
+                )
+            )
+            return user_message, note
         employee = await self._manager_of(organization_id, employee_id)
         extra = "\n\n".join(
             part
@@ -492,6 +511,13 @@ class ManagerTurns:
         )
         return user_message, assistant_message
 
+    async def _out_of_credit(self, organization_id: str) -> bool:
+        """True when a wired wallet shows no credit left (a missing wallet counts as none)."""
+        if self.wallets is None:
+            return False
+        wallet = await self.wallets.get_for_org(organization_id)
+        return wallet is None or wallet.balance <= 0
+
     def _chat_context(
         self,
         *,
@@ -1083,6 +1109,7 @@ class ManagerTurns:
 
 __all__ = [
     "BOOTSTRAP_TIERS",
+    "CHAT_NO_CREDIT_MESSAGE",
     "CHAT_TURN_TIMEOUT_SECONDS",
     "HIRABLE_ROLES",
     "NO_MODEL_GRANTED_MESSAGE",