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/interfaces/realtime/rpc_app.py

@@ -23,6 +23,7 @@ from app.interfaces.http.errors import register_exception_handlers
 from app.interfaces.http.request_context import RequestContextMiddleware
 from app.interfaces.http.routers import (
     admin,
+    admin_credits,
     admin_domains,
     admin_grants,
     admin_users,
@@ -31,6 +32,7 @@ from app.interfaces.http.routers import (
     auth,
     billing,
     delivery,
+    engine,
     health,
     invites,
     knowledge,
@@ -82,6 +84,8 @@ def build_rpc_app() -> FastAPI:
     application.include_router(memory.router, prefix="/api")
     application.include_router(mcp_tokens.router, prefix="/api")
     application.include_router(admin_grants.router, prefix="/api")
+    application.include_router(admin_credits.router, prefix="/api")
+    application.include_router(engine.router, prefix="/api")
     application.include_router(delivery.router, prefix="/api")
     application.include_router(admin_domains.router, prefix="/api")
     application.include_router(sandbox.admin_router, prefix="/api")