E5 S6: enriched person page (TMDB bio + birth facts + Known-for rail)

The person page now leads with a TMDB bio, lazily fetched the first time it's
opened (off the S2-linked `tmdb_person_id`) and then served from the row:

- Migration 0072: ADD-only nullable person columns on plex_people — biography,
  birthday, deathday, place_of_birth, known_for_department, also_known_as,
  known_for ([{tmdb_id, media_type, title}]), tmdb_enriched_at.
- tmdb.py: TmdbClient.fetch_person (/person/{id}+combined_credits), parse_person
  (bio + a popularity-ranked, deduped known_for), apply_person, enrich_person
  (lazy one-shot, key+id guarded, commits, 404 stamps the watermark).
- people.py person_detail: loads the full person row, lazily enriches (best-effort
  — never fails the page), serves the bio fields + resolves known_for to library
  rows by guid (in-library only, popularity order).
- FE PlexPersonView: bio/birth-facts/aka hero + a "Known for" Carousel rail above
  the existing Movies/Shows filmography; PlexPersonDetail type + i18n (en+hu).

Tests: test_plex_person_bio.py (6: parse / lazy-enrich guards / serve) + extended
PlexPersonView.dom.test.tsx + the unknown-name contract in test_plex_person.py.
Browser-E2E'd on Jim Carrey (live TMDB enrich → bio 1937 chars, born 1962-01-17
Newmarket, Known-for resolved). Gate: vitest 337, backend lane 402.

frontend/src/components/PlexPersonView.dom.test.tsx

@@ -85,6 +85,12 @@ describe("PlexPersonView", () => {
     plexPerson.mockResolvedValue({
       name: "Jane Doe",
       photo: null,
+      biography: "A celebrated actor.",
+      birthday: "1970-01-01",
+      place_of_birth: "Springfield",
+      known_for_department: "Acting",
+      also_known_as: ["Janie D"],
+      known_for: [card("kf1", "Famous Film")],
       movies: [card("m1", "Movie One")],
       shows: [card("s1", "Show One", "show")],
     });
@@ -104,13 +110,30 @@ describe("PlexPersonView", () => {
     expect(screen.getByText("plex.person.movies")).toBeTruthy(); // section headings (key passthrough)
     expect(screen.getByText("plex.person.shows")).toBeTruthy();
 
+    // E5 S6 bio hero: department, biography, birth facts, aka.
+    expect(screen.getByText("Acting")).toBeTruthy();
+    expect(screen.getByText("A celebrated actor.")).toBeTruthy();
+    expect(screen.getByText(/1970-01-01/)).toBeTruthy();
+    expect(screen.getByText(/plex\.person\.aka/)).toBeTruthy();
+    expect(screen.getByText(/Janie D/)).toBeTruthy();
+    // "Known for" rail renders its card.
+    expect(screen.getByText("plex.person.knownFor")).toBeTruthy();
+    expect(screen.getAllByText("Famous Film").length).toBeGreaterThan(0);
+
     fireEvent.click(screen.getByText("plex.person.filterBy"));
     expect(onFilter).toHaveBeenCalledWith({ actors: ["Jane Doe"] });
     expect(plexPerson).toHaveBeenCalledWith("Jane Doe");
   });
 
   it("shows the empty message when the person has no titles", async () => {
-    plexPerson.mockResolvedValue({ name: "Nobody", photo: null, movies: [], shows: [] });
+    plexPerson.mockResolvedValue({
+      name: "Nobody",
+      photo: null,
+      also_known_as: [],
+      known_for: [],
+      movies: [],
+      shows: [],
+    });
     wrap(
       <PlexPersonView
         name="Nobody"