burger sub-btns: opacity-0.6 inactive default + 2-pulse --priRd flash w. fa-ban swap on click — TDD

Adds the active/inactive distinction to the 5 burger fan sub-btns. Default state is INACTIVE (opacity 0.6, real icon visible); active conditions get wired one-by-one in later sprints as each surface matures.

## Markup (templates/apps/gameboard/_partials/_burger.html)

Each sub-btn now renders BOTH icons:
- `<i class="fa-solid fa-<real> burger-fan-icon--on">` (sky/earth/sea/voice/text)
- `<i class="fa-solid fa-ban burger-fan-icon--off">`

CSS keeps the real icon visible by default in both .active + inactive states. The fa-ban only surfaces during the .flash-inactive pulse below (icon swap is tied to the pulse class, not to inactive state per se — user-spec'd).

## SCSS (static_src/scss/_burger.scss)

- `#id_burger_btn.active ~ ... .burger-fan-btn.active { opacity: 1 }` — active sub-btn fully visible.
- `#id_burger_btn.active ~ ... .burger-fan-btn:not(.active) { opacity: 0.6 }` — inactive default.
- `.burger-fan-icon--on / --off` stacked absolute-position so the swap doesn't shift the layout box.
- `.burger-fan-btn.flash-inactive` — adds --priRd border + glow (box-shadow modeled on sig-select's SAVE SIG countdown but lighter), AND swaps to fa-ban via `.burger-fan-icon--on { display: none } / --off { display: inline-block }`.

The `#id_burger_btn` itself (the trigger btn) is explicitly NOT subject to inactive/active opacity treatment — only the sub-btns.

## JS (apps/epic/static/apps/epic/burger-btn.js)

Delegated click handler on `#id_burger_fan`: any `.burger-fan-btn` click that DOESN'T carry `.active` runs `_flashInactive(subBtn)` — 2 pulses, 180ms ON / 120ms OFF (tighter than sig-select's 600ms cadence per user spec). Active sub-btns will route to their per-feature handlers in later sprints; for now they no-op.

## Tests

- `apps/epic/tests/integrated/test_views.py::RoomBurgerBtnRenderTest::test_each_sub_btn_renders_dual_icon_for_inactive_flash_swap` — asserts `burger-fan-icon--on` + `--off` appear 5 times each (one per sub-btn). fa-ban itself isn't counted directly — `_table_positions.html` also renders fa-ban for non-starter seats — but the burger-fan-icon classes are unique to the fan.
- `static_src/tests/BurgerSpec.js` — 5 new specs under `describe("inactive sub-btn flash")`:
  - adds .flash-inactive on click
  - removes after ~180ms (first ON window)
  - re-adds after ~480ms (second ON window during the 2nd pulse)
  - settles back to default after ~800ms (full 2-pulse cycle)
  - does NOT flash when sub-btn carries .active

Uses `jasmine.clock()` for deterministic timing. Mirror-copied to `static/tests/BurgerSpec.js` for the Jasmine FT runner.

## Verification

1358 IT+UT green. Jasmine FT runs all specs (incl. the 5 new flash specs) green.

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

src/apps/epic/static/apps/epic/burger-btn.js

@@ -54,14 +54,41 @@
             fan.setAttribute('aria-hidden', 'true');
         }
 
+        // 2 pulses, ~180ms ON / 120ms OFF — tighter cadence than
+        // sig-select's countdown glow (600ms), but same shape.
+        function _flashInactive(subBtn) {
+            var pulses = 2;
+            var onMs = 180;
+            var offMs = 120;
+            function pulse(remaining) {
+                if (remaining <= 0) return;
+                subBtn.classList.add('flash-inactive');
+                setTimeout(function () {
+                    subBtn.classList.remove('flash-inactive');
+                    setTimeout(function () {
+                        pulse(remaining - 1);
+                    }, offMs);
+                }, onMs);
+            }
+            pulse(pulses);
+        }
+
         btn.addEventListener('click', function (e) {
             e.stopPropagation();
             if (_isOpen()) _close();
             else _open();
         }, { signal: sig });
 
+        // Delegated click on the fan — flash --priRd glow twice when an
+        // INACTIVE sub-btn is clicked (its feature isn't wired yet). Active
+        // sub-btns will route to their per-feature handlers in later sprints.
         fan.addEventListener('click', function (e) {
             e.stopPropagation();
+            var subBtn = e.target.closest('.burger-fan-btn');
+            if (!subBtn) return;
+            if (!subBtn.classList.contains('active')) {
+                _flashInactive(subBtn);
+            }
         }, { signal: sig });
 
         document.addEventListener('keydown', function (e) {

src/apps/epic/tests/integrated/test_views.py

@@ -2585,6 +2585,19 @@ class RoomBurgerBtnRenderTest(TestCase):
         ):
             self.assertContains(response, icon)
 
+    def test_each_sub_btn_renders_dual_icon_for_inactive_flash_swap(self):
+        """Sub-btns carry BOTH the real icon (.burger-fan-icon--on) + a
+        fa-ban placeholder (.burger-fan-icon--off). CSS keeps the real
+        icon visible by default; .flash-inactive swaps to fa-ban during
+        the click-while-inactive pulse. fa-ban itself isn't counted
+        directly — _table_positions.html also renders fa-ban for
+        non-starter seats — but the burger-fan-icon classes are unique
+        to the fan + load-bearing for the CSS swap rule."""
+        response = self.client.get(self.url)
+        body = response.content.decode()
+        self.assertEqual(body.count("burger-fan-icon--on"), 5)
+        self.assertEqual(body.count("burger-fan-icon--off"), 5)
+
     def test_burger_btn_script_loaded(self):
         response = self.client.get(self.url)
         self.assertContains(response, "burger-btn.js")