remove obsolete skipped tests; fix billboard applet menu containment; align landscape menus

Deleted skips:
- test_fan_next_button_advances_card (T11) + test_fan_remembers_position_on_reopen (T13):
  fan-nav nav button obstruction — deferred indefinitely, not worth tracking
- test_selected_sig_card_removed_from_deck_for_other_gamers (S5): card count
  mismatch in channels context — grand overhaul pending, obsolete with new sig-select
- Removed stale TODO comment about #id_inv_sig_card (element no longer exists)
- Dropped unused `import unittest` from test_room_sig_select.py

billboard applet menu fix: moved #id_billboard_applet_menu out of
#id_billboard_applets_container — container-type:inline-size was making the
container a containing block for fixed-position descendants, clipping the menu.

Landscape menu alignment: all applet menus now right:0.5rem (flush with gear/kit
buttons in the 4rem right sidebar); added #id_room_menu to the landscape rule.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/templates/apps/billboard/_partials/_applets.html

@@ -1,27 +1,27 @@
+<div id="id_billboard_applet_menu" style="display:none;">
+    <form
+        hx-post="{% url "billboard:toggle_applets" %}"
+        hx-target="#id_billboard_applets_container"
+        hx-swap="outerHTML"
+    >
+        {% csrf_token %}
+        {% for entry in applets %}
+            <label>
+                <input
+                    type="checkbox"
+                    name="applets"
+                    value="{{ entry.applet.slug }}"
+                    {% if entry.visible %}checked{% endif %}
+                >
+                {{ entry.applet.name }}
+            </label>
+        {% endfor %}
+        <div class="menu-btns">
+            <button type="submit" class="btn btn-confirm">OK</button>
+            <button type="button" class="btn btn-cancel applet-menu-cancel">NVM</button>
+        </div>
+    </form>
+</div>
 <div id="id_billboard_applets_container">
-    <div id="id_billboard_applet_menu" style="display:none;">
-        <form
-            hx-post="{% url "billboard:toggle_applets" %}"
-            hx-target="#id_billboard_applets_container"
-            hx-swap="outerHTML"
-        >
-            {% csrf_token %}
-            {% for entry in applets %}
-                <label>
-                    <input
-                        type="checkbox"
-                        name="applets"
-                        value="{{ entry.applet.slug }}"
-                        {% if entry.visible %}checked{% endif %}
-                    >
-                    {{ entry.applet.name }}
-                </label>
-            {% endfor %}
-            <div class="menu-btns">
-                <button type="submit" class="btn btn-confirm">OK</button>
-                <button type="button" class="btn btn-cancel applet-menu-cancel">NVM</button>
-            </div>
-        </form>
-    </div>
     {% include "apps/applets/_partials/_applets.html" %}
 </div>