feat(WP-67): merge behandelportal into this repo as a monorepo

Restructures into apps/ssp + apps/behandelportal (two Angular projects)
plus libs/shared + libs/beheer (cross-app libraries), replacing WP-61's
separate sibling repo. That split had already produced real drift: a
hand-vendored copy of the backend's OpenAPI doc, a shared/ui+layout tree
forked and silently diverging (7 files), and beheer + the styles.scss
token bridge duplicated byte-for-byte across both repos.

- git mv the SSP's src/app/* into apps/ssp/; fold shared/, beheer/,
  environments/, the Storybook docs/*.mdx, and styles.scss into
  libs/shared + libs/beheer (all confirmed identical between the two
  repos before merging). auth stays deliberately duplicated per
  ADR-0002 (actor-specific, expected to diverge) - amended there.
- One generated API client (libs/shared), no more vendored swagger.json.
- .dependency-cruiser split into a base factory + one config per app,
  and Storybook into .storybook-ssp/.storybook-behandelportal - both
  forced by the @auth/* alias resolving to different directories per app.
- SiteHeaderComponent/ShellComponent gained HEADER_NAV_ITEMS/
  HEADER_ADMIN_LINKS/DEBUG_PANEL injection tokens so each app supplies
  its own nav/admin-links/dev-panel instead of one being hardcoded.
- CLAUDE.md, ARCHITECTURE.md, dependencies.md, and ADR-0002 updated;
  WP-67 backlog entry documents the full decision trail.

npm run ci green (lint, dep:check x2, 360 tests across ssp/
behandelportal/shared/beheer, both localized builds, backend tests,
snippet + api-client drift); both dev servers, both Storybook
instances, and docker compose verified working.

The old sibling repo (/home/eho/repos/behandelportal) is left
untouched, not deleted.

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

libs/shared/src/application/session.port.ts

@@ -0,0 +1,14 @@
+import { InjectionToken, Signal } from '@angular/core';
+
+/**
+ * A shared seam for the chrome to show "who is logged in" + log out, WITHOUT
+ * shared/ depending on the auth context (the import-direction rule forbids that).
+ * Auth provides this token at the app root (see app.config.ts); the shared header
+ * injects it. SessionStore satisfies this shape structurally.
+ */
+export interface SessionPort {
+  readonly session: Signal<{ naam: string } | null>;
+  logout(): void;
+}
+
+export const SESSION_PORT = new InjectionToken<SessionPort>('SESSION_PORT');