WARDEN-WP-0026 finish Strand A (T04/T05/T07)

Promote railiance-backup-offsite-lane to active/resolvable after
capabilities-safe re-verify. Add catalog risk=high, agent read-boundary
(exit 7 + OpenBao policy companion), EXPOSED taint via warden taint, and
close WP-0026.

src/warden/routing/catalog.py

@@ -22,7 +22,7 @@ from typing import List, Optional
 
 import yaml
 
-from warden.routing.models import RotationGuide, RouteEntry
+from warden.routing.models import VALID_RISK, RotationGuide, RouteEntry
 
 # Structured handoff string fields (WP-0014) — templates and pointers only.
 # Every one is scanned for accidental secret material; see _assert_no_secret_material.
@@ -303,6 +303,12 @@ def _parse_entry(raw: dict, index: int) -> RouteEntry:
             f"entry {entry_id!r} has invalid lane {lane!r} (expected one of {_VALID_LANES})"
         )
 
+    risk = str(raw.get("risk", "standard")).strip() or "standard"
+    if risk not in VALID_RISK:
+        raise CatalogError(
+            f"entry {entry_id!r} has invalid risk {risk!r} (expected one of {VALID_RISK})"
+        )
+
     return RouteEntry(
         id=entry_id,
         title=str(raw["title"]),
@@ -326,6 +332,7 @@ def _parse_entry(raw: dict, index: int) -> RouteEntry:
         exec_command=handoff["exec_command"],
         pointer_command=handoff["pointer_command"],
         rotation=_parse_rotation(entry_id, raw.get("rotation")),
+        risk=risk,
     )