Scale the blocker window by lane risk, converging with risk-nexus

risk-nexus accepted the offer to match their convention rather than grow a second
one, and published it: 14d critical/high, 30d medium, 60d low, nothing auto-closing
on staleness alone. Their preference — point warden route gaps at those windows and
the two registers agree without a shared mechanism — is better than a joint tool.

blocker_stale_days() now maps lane risk onto those windows. A flat 14 would have
been wrong in both directions: too aggressive for a low-risk pointer, and it treated
an admin PAT lane the same as one.

ungraded takes the shortest window, not the longest. ADR-0007 makes an absent grade
a defect and ADR-0008 makes a grade cover the whole path, so a lane nobody graded is
the one whose blocker deserves least trust. Encoding that as 60 days would have been
the fail-open default this repo already fixed once.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

workplans/WARDEN-WP-0033-native-lane-handoff.md

@@ -222,6 +222,15 @@ fire before November.
    `RISK-F-0001`, ~50 for `FLEX-WP-0007`. At ~15 lanes it surfaces about one a
    day rather than a wall, and it fires on zero lanes on age today.
 
+   **Then scaled by risk, after risk-nexus answered.** They accepted the offer to
+   converge and published their convention: 14 days critical/high, 30 medium, 60
+   low, with fix state *read* from the owning repo rather than remembered. Their
+   framing — "point `warden route gaps` at those windows and the two will agree
+   without either of us building a shared mechanism" — is better than a joint
+   tool, so `blocker_stale_days()` now maps lane `risk` onto exactly those
+   windows. `ungraded` takes the *shortest*, not the longest: `ADR-0007` makes an
+   absent grade a defect, so its blocker is the least trustworthy of all.
+
 2. **`verified:` distinguishes re-checking from re-editing.** `reviewed` records
    when someone touched the entry; nothing recorded whether the claim was
    re-established. `owner-confirmed` and `source-read` count;