brief sprint C1: relocate Post + Line from dashboard → billboard (no behavior change) — TDD

The Post/Line models always read more like billboard tenants than dashboard ones (1st-person personal vs. 2nd-person provenance feed); the upcoming Brief model needs them in the billboard namespace as the canonical surface they FK into. C1 is a pure relocation w. zero new behavior: 789 ITs + 20 sky/Post FTs green against the moved code.

- billboard.models adds Post (owner + shared_with) + Line (text + post FK), schema mirroring the legacy dashboard models 1:1; Post.get_absolute_url now reverses to `billboard:view_post`.
- billboard.forms adds LineForm + ExistingPostLineForm (moved from dashboard.forms; dashboard/forms.py removed).
- billboard.views absorbs new_post / view_post / share_post / my_posts (templates rendered from apps/billboard/post.html + my_posts.html).
- billboard.urls adds the namespaced routes: /billboard/new-post, /billboard/post/<uuid>/, /billboard/post/<uuid>/share-post, /billboard/users/<uuid>/. dashboard.urls drops the corresponding entries.
- _applet-my-posts + _applet-new-post URL refs now use the billboard: namespace; templates/apps/dashboard/{post,my_posts}.html removed.
- api/serializers + api/views + api/tests/integrated/test_views imports flip dashboard.models → billboard.models (PostSerializer / PostDetailAPI / PostLinesAPI / PostsAPI all retain identifiers — the model rename to Brief lands in C2).
- dashboard/tests/integrated/test_{models,views,forms} + dashboard/tests/unit/test_{models,forms} swap imports; test_views URL strings flip /dashboard/post/ → /billboard/post/, /dashboard/new_post → /billboard/new-post, /dashboard/users/ → /billboard/users/, share_post → share-post (path) / billboard:share_post (reverser). Tests stay in dashboard.tests/ for now — relocation TBD.
- functional_tests/my_posts_page.py URL string flips to /billboard/users/.
- Auto-generated migrations: billboard/0001_initial (CreateModel Post + Line), dashboard/0003_remove_post_* (drops legacy Post + Line), drama/0004_alter_gameevent_verb (incidental — choices field caught up).

This commit drops the dashboard Post/Line tables w/o data preservation; user has confirmed staging-side wipe is acceptable. C2 introduces the Brief model + read-tracking + slide-down banner unification. C3 hooks Note-unlock + share-post-invite + magic-link / invalid-link `messages` calls into the new Brief / banner pipeline.

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

src/apps/billboard/migrations/0001_initial.py

@@ -0,0 +1,38 @@
+# Generated by Django 6.0 on 2026-05-08 21:11
+
+import django.db.models.deletion
+import uuid
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Post',
+            fields=[
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('owner', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='posts', to=settings.AUTH_USER_MODEL)),
+                ('shared_with', models.ManyToManyField(blank=True, related_name='shared_posts', to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Line',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('text', models.TextField(default='')),
+                ('post', models.ForeignKey(default=None, on_delete=django.db.models.deletion.CASCADE, related_name='lines', to='billboard.post')),
+            ],
+            options={
+                'ordering': ('id',),
+                'unique_together': {('post', 'text')},
+            },
+        ),
+    ]