security(discovery): enforce Zone isolation and retire unsafe legacy writers

Bind Agent observations, review, enrichment and telemetry to current Zone
and inventory authority. Preserve immutable MAC ownership and historical
snapshots with stale-result rejection and transactional security audits.

Retire unbound direct/range/scheduled discovery and one/bulk legacy summary
writes in both modes. Require reconciled exact inventory identity or
explicit Zone-scoped IP selection for CSV metadata imports.

Independent Blocker #1 application-security re-audit: PASS on tree
cf863aadc9. Evidence: 141 focused PostgreSQL/HTTP
tests passed; Chromium and PowerShell checks passed. Two documented baseline
source assertions remain unchanged. Production deployment is not approved.

backend/app/discovery/http.py

@@ -0,0 +1,42 @@
+"""Bounded HTTP adapter; authentication remains on the registered routes."""
+
+import json
+from fastapi import HTTPException
+from starlette.concurrency import run_in_threadpool
+import psycopg
+from app.discovery.repository import DiscoveryRepository
+
+MAX_BODY = 1024 * 1024
+
+
+async def dispatch(method, request=None, **kwargs):
+    if request is not None:
+        chunks = []
+        size = 0
+        async for chunk in request.stream():
+            size += len(chunk)
+            if size > MAX_BODY:
+                raise HTTPException(413, "discovery_payload_too_large")
+            chunks.append(chunk)
+        try:
+
+            def invalid_constant(_):
+                raise ValueError("Non-finite JSON number")
+
+            kwargs["body"] = json.loads(
+                b"".join(chunks), parse_constant=invalid_constant
+            )
+        except (ValueError, UnicodeDecodeError, RecursionError):
+            raise HTTPException(422, "discovery_invalid_json")
+    try:
+        return await run_in_threadpool(getattr(DiscoveryRepository(), method), **kwargs)
+    except (
+        psycopg.errors.LockNotAvailable,
+        psycopg.errors.QueryCanceled,
+        psycopg.errors.DeadlockDetected,
+    ):
+        raise HTTPException(409, "discovery_concurrent_change_retry")
+    except psycopg.DataError:
+        raise HTTPException(422, "discovery_invalid_value")
+    except psycopg.IntegrityError:
+        raise HTTPException(409, "discovery_identity_conflict")