fix(scaffolding): rename create-ssp to create-frontend, fix 2 bugs it surfaced

Renamed scripts/create-ssp.mjs -> create-frontend.mjs (+ its WP-45 doc, npm
script, and every prose/command reference) since "ssp" reads as an acronym
where "create-frontend" says what it does.

Also fixes two real bugs found while running it for real during WP-61:
scripts/ci-local.sh was missing from RENAME_CONTENT_FILES (any --name'd
clone that keeps a backend would break `npm run ci`, still hardcoding
BigRegister.slnx), and plopfile.mjs's `gen:context` insertion into
.dependency-cruiser.js anchored on the `showcase: null,` line, which
create-ssp/create-frontend has already stripped by the time gen:context
runs in the same invocation — silently leaving a freshly scaffolded
context with no CONTEXT_ALLOWED fence entry at all. Re-anchored on the
`const CONTEXT_ALLOWED = {` line instead, which never moves.

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

package.json

@@ -24,7 +24,7 @@
     "gen:value-object": "plop value-object",
     "gen:form-machine": "plop form-machine",
     "gen:context": "plop context",
-    "create-ssp": "node scripts/create-ssp.mjs",
+    "create-frontend": "node scripts/create-frontend.mjs",
     "serve:i18n": "ng build --configuration development --localize && node scripts/serve-i18n.mjs",
     "ci": "bash scripts/ci-local.sh",
     "e2e": "playwright test",