note title equip: DON/DOFF buttons outside top-left corner; User.active_title FK; don/doff views; greeting updated via JS — TDD

- lyric/models.py: active_title = ForeignKey('drama.Note', null=True, SET_NULL)
- lyric migration 0020_add_active_title
- billboard/views.py: don_title + doff_title views; is_equipped per note_item context
- billboard/urls.py: note/<slug>/don + note/<slug>/doff routes
- _navbar.html: id_greeting_name span; shows active_title.slug|capfirst when set
- my_notes.html: .note-don-doff buttons (DON/DOFF, × when disabled); data-don-url/doff-url/title attrs
- note-page.js: _bindDonDoff() — DON POST sets greeting + swaps btn state; DOFF restores Earthman
- _note.scss: .note-don-doff position:absolute left:-1rem top:0; flex-direction:column gap:1.25rem
- ITs: NoteEquipTitleViewTest (5 tests); UserModelTest.test_active_title_* (3 tests)
- FT: NoteEquipTitleTest.test_don_equips_title_greeting_and_doff_restores

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/apps/billboard/views.py

@@ -137,6 +137,7 @@ def note_set_palette(request, slug):
 @login_required(login_url="/")
 def my_notes(request):
     qs = Note.objects.filter(user=request.user)
+    active_title = request.user.active_title
     note_items = [
         {
             "obj":             n,
@@ -144,6 +145,7 @@ def my_notes(request):
             "description":     _NOTE_META.get(n.slug, {}).get("description", ""),
             "palette_options": _NOTE_META.get(n.slug, {}).get("palette_options", []),
             "palette_label":   _PALETTE_LABELS.get(n.palette, "") if n.palette else "",
+            "is_equipped":     active_title is not None and active_title.pk == n.pk,
         }
         for n in qs
     ]
@@ -154,6 +156,28 @@ def my_notes(request):
     })
 
 
+@login_required(login_url="/")
+def don_title(request, slug):
+    from django.http import Http404
+    try:
+        note = Note.objects.get(user=request.user, slug=slug)
+    except Note.DoesNotExist:
+        raise Http404
+    if request.method == "POST":
+        request.user.active_title = note
+        request.user.save(update_fields=["active_title"])
+    title = _NOTE_META.get(slug, {}).get("title", slug.capitalize())
+    return JsonResponse({"title": title})
+
+
+@login_required(login_url="/")
+def doff_title(request, slug):
+    if request.method == "POST":
+        request.user.active_title = None
+        request.user.save(update_fields=["active_title"])
+    return JsonResponse({"ok": True})
+
+
 @login_required(login_url="/")
 def save_scroll_position(request, room_id):
     if request.method != "POST":