refactor: ui/dashboard becomes ui/overzicht-secties (RD-36)

RD-03 moved the dashboard page to overzicht/ui/overzicht.page.ts and left four
sections in registratie/ui/dashboard/. The folder was named after a page that
lives in another context. A reader who opened it found four sections that are
not the dashboard.

The folder is now overzicht-secties/ — registratie's sections for the overzicht
page. The alias does not change, because the sections stay in the registratie
context. The story titles do not change, because they name the context.

Five documents cited registratie/ui/dashboard.page.ts, a file that RD-03
renamed. They now name overzicht.page.ts, or the section that owns the
behaviour they describe.

The /dashboard route keeps its path. It is a user-visible URL.

npm run ci --full passes: 67 and 45 storybook suites, 306 axe tests.

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

.claude/skills/new-ssp/SKILL.md

@@ -62,7 +62,7 @@ Work through that checklist, keeping the GREEN gate below passing at every step.
   re-target it at an arbitrary new context, so it's deleted alongside `registratie`, along
   with its three wiring lines in `shell.component.ts` (import, `imports:` entry, template tag).
 - The `dashboard` route is **not** deleted even though it currently imports
-  `@registratie/ui/dashboard.page` — too much else hardcodes `/dashboard` (login's post-auth
+  `@overzicht/ui/overzicht.page` — too much else hardcodes `/dashboard` (login's post-auth
   redirect, `authGuard`'s fallback, header nav/logo, breadcrumb trail, several stories/specs).
   The script rewrites its `loadComponent` to point at the freshly scaffolded `--context` page
   instead (a `TODO(create-frontend)` stopgap landing page, not a real overview).