My Sign DEL btn: clear-sign affordance on SCAN SIGN landing — Sprint 4b-adjacent of My Sea roadmap — TDD

Pre-spec'd in [[sprint-my-sea-sign-gate-may19]] as the unblocker for tomorrow's visual verification of 4b's no-sig branch — admin user (@disco) had a saved sig from Sprint 4a testing & there was no in-UI affordance to undo it short of DB surgery. Lands ahead of the deferred 4b visual verify so dev users can toggle between sig/no-sig states on Claudezilla.

- Endpoint: `path("my-sign/clear", views.clear_sign, name="clear_sign")` — POST sets `User.significator = None` + `significator_reversed = False`, redirects to picker; GET is a no-mutation redirect to picker (mirrors save_sign's GET handling). `login_required(login_url="/")`. No trailing slash per [[feedback_url_convention_actions_no_trailing_slash]] (action endpoint, not page).
- Template (my_sign.html): `<form id="id_clear_sign_form" class="my-sign-clear-form">` w. `<button id="id_clear_sign_btn" class="btn btn-danger">DEL</button>`, rendered ONLY when `current_significator` is set; sits inside `.my-sign-landing` as a sibling of `.room-shell` so it's bound to the landing-phase UI alone (picker phase already has its own NVM unlock affordance on focused thumbnails).
- SCSS: anchored bottom-right of `.my-sign-landing` via `position: absolute; bottom: .75rem; right: 1rem` — `.my-sign-landing` gains `position: relative` to scope the absolute. `.btn-danger` carries the destructive treatment; "DEL" mirrors post.html gear menu's DEL convention from [[sprint-post-polish-may13]].
- 3 FTs in new `MySignClearTest` class — covers: btn renders on landing when sig saved (T1, asserts text "DEL" + `.btn-danger` class); btn absent when no sig (T2); click POSTs, reloads, & wipes `User.significator` + `significator_reversed` in DB (T3).
- 6 ITs in new `ClearSignViewTest` + `MySignClearAffordanceTemplateTest` — covers: login_required gate, POST wipes both fields w. redirect-back, GET redirects w.o mutation, POST-w/o-existing-sig is idempotent no-op, template renders btn only when sig set, template's form action targets `clear_sign` reverse.
- 1029 IT/UT green in 47s (+6 from baseline); 20/20 FT green across test_bill_my_sign + test_game_my_sea in 165s.

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

src/static_src/scss/_card-deck.scss

@@ -668,6 +668,7 @@ html:has(.sig-backdrop) {
     flex: 1;
     min-height: 0;
     display: flex;
+    position: relative;
 
     // SCAN SIGN btn — centered in the hex. Default .btn-primary text
     // (0.875rem) scales tighter than the room's PICK SIGS btn font; this
@@ -678,6 +679,17 @@ html:has(.sig-backdrop) {
         line-height: 1.1;
         white-space: normal;
     }
+
+    // DEL btn — destructive secondary action, only rendered when a sig
+    // is saved. Anchored bottom-right of the landing area so it doesn't
+    // compete w. the centered SCAN SIGN hex for visual weight. .btn-danger
+    // for the destructive treatment (mirrors post.html gear menu DEL).
+    .my-sign-clear-form {
+        position: absolute;
+        bottom: 0.75rem;
+        right: 1rem;
+        margin: 0;
+    }
 }
 
 // Hide SAVE SIGN on landing — the form only makes sense once the user