test: register wave-4 carves (office-hours ext, design-html, design-shotgun) — 20 carved skills

Both design entries carry requiredReads + loading-eval scenarios (D3A
condition). office-hours phase sections are mode-exclusive, so only the
always-reached design/handoff section is a deterministic requiredRead.
Baselines and ratchet recaptured.

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

test/fixtures/context-budget.json

@@ -14,9 +14,9 @@
     "context-save": 9551,
     "cso": 14524,
     "design-consultation": 12985,
-    "design-html": 15001,
+    "design-html": 12841,
     "design-review": 23567,
-    "design-shotgun": 14031,
+    "design-shotgun": 13028,
     "devex-review": 14924,
     "diagram": 3847,
     "document-generate": 11679,
@@ -36,7 +36,7 @@
     "landing-report": 8844,
     "learn": 8514,
     "make-pdf": 4957,
-    "office-hours": 21191,
+    "office-hours": 17468,
     "open-gstack-browser": 4429,
     "openclaw/skills/gstack-openclaw-ceo-review": 2764,
     "openclaw/skills/gstack-openclaw-investigate": 1429,