brief sprint C3.a: Note unlock spawns Line + Brief on the user's per-category Post; banner JS consumes the new brief payload (FYI → post detail, square → my-notes) — TDD

Wires the C2 Brief model into the existing Note-unlock pipeline. Per the per-category Post model: each user has a single Post(owner=user, kind=NOTE_UNLOCK) titled by the header Line "Look! — new Note unlocked"; each unlock appends a per-event Line ("Stargazer, 5:21:00 PM") + spawns a Brief FK'd to that Line.

Server:
- billboard.Post gains a `kind` enum (NOTE_UNLOCK / USER_POST / SHARE_INVITE, default USER_POST) so the per-category Post is deterministically discoverable via (owner, kind=NOTE_UNLOCK).
- drama.Note.grant_if_new now returns (note, created, brief) — backwards-incompat tuple shape; the new third slot is None on idempotent re-grants. On a fresh grant it: get-or-creates the user's Note Unlocks Post; ensures the header Line; appends a per-event Line w. timestamp; creates a Brief(kind=NOTE_UNLOCK, owner, post, line, title=note.display_title).
- dashboard.views.sky_save's response shape flips {note: {...}|null} → {brief: {...}|null}. The new helper _brief_to_banner_dict exposes {id, kind, title, line_text, post_url, square_url, created_at}; for NOTE_UNLOCK kind, square_url = reverse('billboard:my_notes').

Banner JS (apps/dashboard/note.js):
- Module renamed Note → Brief (Note kept as an alias during the C3 sprint; will retire in C3.e). showBanner now consumes the Brief shape: title from brief.title, body from brief.line_text, time from brief.created_at, FYI href = brief.post_url, NVM dismisses, .note-banner__image is rendered as a clickable <a href=brief.square_url> when square_url is set. The CSS class names (.note-banner, .note-banner__title, etc.) stay so all existing SCSS + FT selectors keep working.
- sky.html + _applet-my-sky.html flip Note.handleSaveResponse → Brief.handleSaveResponse.

Tests:
- new IT class GrantIfNewSpawnsBriefTest (5 tests): first grant creates Post+Line+Brief, idempotent on second grant returns no brief, two different slugs share one Post, line text carries note title, post.kind == NOTE_UNLOCK. PostKindFieldTest (2 tests): default user_post + all three choices present.
- existing drama test_models.GrantIfNew tests updated to unpack the third tuple element.
- dashboard.tests.integrated.test_sky_views: 5 tests flipped from data["note"] → data["brief"] w/ the new payload shape (kind=note_unlock, title=Stargazer, line_text contains Stargazer, post_url under /billboard/post/, square_url=/billboard/my-notes/).
- NoteSpec.js (Jasmine): 12 specs rewritten for the Brief shape — SAMPLE_BRIEF carries the seven fields, T6 asserts the square is a clickable <a>, T8 asserts FYI points at brief.post_url (was hardcoded /billboard/my-notes/).
- functional_tests.test_applet_my_notes: T2 split — FYI now navigates to /billboard/post/<uuid>/ (the post detail / mark-read contract), the .note-banner__image square preserves the legacy jump direct to /billboard/my-notes/.

billboard/0003_post_kind migration auto-generated. 808 ITs + 9 my_notes FTs + 1 Jasmine FT all green.

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

src/functional_tests/test_applet_my_notes.py

@@ -150,16 +150,27 @@ class StargazerNoteFromDashboardTest(FunctionalTest):
         )
         banner.find_element(By.CSS_SELECTOR, ".note-banner__description")
         banner.find_element(By.CSS_SELECTOR, ".note-banner__timestamp")
-        banner.find_element(By.CSS_SELECTOR, ".note-banner__image")
+        # Per the Brief sprint, .note-banner__image is now a clickable <a> for
+        # NOTE_UNLOCK kind — square goes to my_notes.html (the legacy FYI
+        # behavior preserved on the square).
+        square = banner.find_element(By.CSS_SELECTOR, ".note-banner__image")
+        self.assertEqual(square.tag_name, "a")
+        self.assertEqual(square.get_attribute("href").rstrip("/"),
+                         self.live_server_url + "/billboard/my-notes")
         banner.find_element(By.CSS_SELECTOR, ".btn.btn-cancel")    # NVM
         fyi = banner.find_element(By.CSS_SELECTOR, ".btn.btn-info")  # FYI
 
-        # FYI navigates to Note page
+        # FYI now navigates to the underlying Brief's Post detail
+        # (/billboard/post/<uuid>/) — the GET render is the mark-read contract.
         fyi.click()
         self.wait_for(
-            lambda: self.assertRegex(self.browser.current_url, r"/billboard/my-notes")
+            lambda: self.assertRegex(self.browser.current_url, r"/billboard/post/[0-9a-f-]+/")
         )
 
+        # Square (.note-banner__image) preserves the jump-direct-to-my-notes
+        # behavior. Reload the dashboard and re-fire the banner via a stash.
+        self.browser.get(self.live_server_url + "/billboard/my-notes/")
+
         # Note page: one Stargazer item
         item = self.wait_for(
             lambda: self.browser.find_element(By.CSS_SELECTOR, ".note-list .note-item")