refactor: add successOr, sweep remaining inline unwraps (RD-17)

Eight sites hand-rolled `rd.tag === 'Success' ? rd.value : fallback`. Six
take the new `successOr(rd, fallback)`, one takes the existing `successOf`,
and one (`big-profile.store.ts`) uses the existing `map`, since it returns a
RemoteData rather than an unwrapped value.

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

apps/ssp/src/app/registratie/application/big-profile.store.ts

@@ -52,10 +52,12 @@ export class BigProfileStore {
   );
 
   /** Specialisms/notes stay a separate stream (they have their own empty state). */
-  readonly aantekeningen = computed<RemoteData<Err, Aantekening[]>>(() => {
-    const rd = fromResource(this.aantekeningenRes, (v) => !v || v.length === 0);
-    return rd.tag === 'Success' ? { tag: 'Success', value: rd.value ?? [] } : rd;
-  });
+  readonly aantekeningen = computed<RemoteData<Err, Aantekening[]>>(() =>
+    map(
+      fromResource(this.aantekeningenRes, (v) => !v || v.length === 0),
+      (v) => v ?? [],
+    ),
+  );
 
   // --- Optimistic herregistratie state, shared with the dashboard -----------
   private pending = signal(false);