feat(profiles): prune the gstack catalog, add max, honor a removed denylist

Nine gstack skills leave every profile (ship is trunk-based on Gitea,
land-and-deploy auto-merges and deploys, setup-deploy, autoplan reads
paths that do not exist here, context-save has no restore, learn is an
unused parallel store, careful and guard hooks never fired, design-shotgun
needs an absent OpenAI key). lib/gstack-removed.sh is the single denylist;
profile.sh gstack on and toggle-external.sh enable gstack skip it.

full now carries everything every other profile carries (user rule), minus
the parked make-pdf, diagram and 21st-ai/ui-explore/ui-review, which live
in the new max profile together with pr-review-toolkit. The 21st trio also
leaves web, web-full and design (redundant with impeccable + ui-ux-pro-max).

lib/tests/profile-census.test.sh asserts the invariants live and on a
baseline fixture plus one mutant per invariant; gstack-removed.test.sh
covers both restore paths.

lib/profiles/design.profile

@@ -11,13 +11,12 @@
 # GATE-BLOCK: 21st 21st-ui-build
 
 # Core design skills (gstack)
-design-shotgun
 design-review
 design-consultation
 design-html
 plan-design-review
 
-# Browser tooling — design-review and design-shotgun rely on it
+# Browser tooling — design-review relies on it
 browse
 open-gstack-browser
 setup-browser-cookies
@@ -44,10 +43,7 @@ site-motion                       personal
 # External: 21st.dev pack — CLI-driven (no MCP, no API key). 21st-registry
 # and 21st-design-sync are publishing flows; installed but left parked.
 21st-ui-build                     external
-21st-ui-explore                   external
-21st-ui-review                    external
 21st-cli-use                      external
-21st-ai                           external
 
 # Plugin (auto-toggle)
 ui-ux-pro-max                     plugin@ui-ux-pro-max-skill