feat(auth): authorization catalogues + Principal builder skeleton (ADR-0025)

Per ADR-0025's implementation phasing, lands the closed-set
catalogues + the OIDC-callback hook that composes the
session-resident Principal. No new guards yet.

- libs/shared/auth: framework-agnostic lib hosting
  authorization.types.ts (4 privileges + 24 functional roles + 6
  scope kinds + Principal type) and entra-group-to-role.ts
  (validated GUID -> slug resolver). 17 unit tests against the
  catalogues + resolver contracts.
- BFF: PrincipalBuilder composes the three axes once at sign-in;
  ScopeResolver seam (StubScopeResolver returns unrestricted in
  v1, replaced by a Prisma-backed implementation when ADR-0026's
  user_scopes table lands). 19 persona-driven tests covering the
  test tenant's full provisioning + edge cases (unknown
  privilege drift, unknown group GUID, empty permissions).
- AuthService extracts the Entra "groups" claim; AuthenticatedUser
  grows the groups: readonly string[] field.
- SessionEstablisher builds + persists the principal alongside
  the legacy user shape (additive — guards consuming user.oid
  unchanged).
- ENTRA_GROUP_MAP_PATH env var + load-entra-group-map.ts read
  the tenant-private map from infra/<env>-tenant.entra.json
  (gitignored; .example.json committed with the schema).
- ADR-0025 path references updated from libs/feature/auth
  (Angular-scoped, scope:portal-shell) to libs/shared/auth
  (consumable by both BFF and SPA).
- notes/entra-groups-claim-activation.md: operator runbook for
  the "Token configuration -> Add groups claim" step in the
  Entra admin centre.

Test plan:
- pnpm nx affected -t lint test build : 13 projects green
  (497 BFF tests + 17 shared-auth tests + 1 shared-util test +
  full lint + full build).

libs/shared/auth/tsconfig.spec.json

@@ -0,0 +1,22 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../../../dist/out-tsc",
+    "types": ["vitest/globals", "vitest/importMeta", "vite/client", "node", "vitest"]
+  },
+  "include": [
+    "vite.config.ts",
+    "vite.config.mts",
+    "vitest.config.ts",
+    "vitest.config.mts",
+    "src/**/*.test.ts",
+    "src/**/*.spec.ts",
+    "src/**/*.test.tsx",
+    "src/**/*.spec.tsx",
+    "src/**/*.test.js",
+    "src/**/*.spec.js",
+    "src/**/*.test.jsx",
+    "src/**/*.spec.jsx",
+    "src/**/*.d.ts"
+  ]
+}