feat(integration): wire v2 workstreams together (engine policy/budget, sandbox, tenant checks, order route, docs)

Engine honours org policy and monthly budget, legacy runner skips engine tasks,
sandbox session provisioned on demand, project fallback for threads, reviewer
fallback, tenant checks on project ids, memory reflection respects grants,
expiry worker, MCP pipeline_status, login redirect, sharing settings, e2e smoke.

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

apps/api/app/infrastructure/repositories/engine.py

@@ -14,6 +14,8 @@ cannot both win — the loser sees zero updated rows and gets a
 
 from __future__ import annotations
 
+from datetime import datetime
+
 from sqlalchemy import func, select, update
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -489,10 +491,11 @@ class GateResultRepository:
 
 
 class TaskSpendRepository:
-    """Per-task spend, read from the usage ledger (never written here).
+    """Spend, read from the usage ledger (never written here).
 
-    The scheduler's budget guard needs "how much has this task cost so far",
-    which the ledger can answer by joining its events to the task's runs. The
+    The scheduler's budget guards need "how much has this task cost so far"
+    (joining the ledger's events to the task's runs) and "how much has this
+    organization spent since a date" (the owner's monthly credit budget). The
     ledger stays the source of truth; this only reads it.
     """
 
@@ -505,3 +508,11 @@ class TaskSpendRepository:
             UsageEventRow.run_id.in_(run_ids)
         )
         return float((await self.session.execute(stmt)).scalar_one())
+
+    async def spend_for_org_since(self, organization_id: str, since: datetime) -> float:
+        """What the organization's usage has cost since ``since``, over all its tasks."""
+        stmt = select(func.coalesce(func.sum(UsageEventRow.total_price), 0.0)).where(
+            UsageEventRow.organization_id == organization_id,
+            UsageEventRow.created_at >= since,
+        )
+        return float((await self.session.execute(stmt)).scalar_one())