natus tooltip: fix portal placement + viewport clamping + SVG sign icon

- Move #id_natus_tooltip out of #id_applets_container (container-type:
  inline-size breaks position:fixed) → add to home.html alongside
  #id_tooltip_portal
- Move #id_natus_tooltip out of .natus-modal-wrap (transform breaks
  position:fixed) → place as sibling of .natus-overlay in room.html
- Add _positionTooltip() helper in natus-wheel.js: flips tooltip to
  left of cursor when it would overflow right edge; clamps both axes
- Replace hardcoded 280px in dashboard.js palette tooltip with measured
  offsetWidth; add left-edge floor (Math.max margin)
- Planet tooltip format: @14.0° Capricorn (<svg-icon>) using preloaded
  _signPaths; falls back to unicode symbol if not yet loaded
- Add .tt-sign-icon SCSS: fill:currentColor, vertical-align:middle

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

src/templates/apps/dashboard/_partials/_applet-my-sky.html

@@ -74,7 +74,6 @@
     {% endif %}
 </section>
 
-<div id="id_natus_tooltip" class="tt" style="display:none;"></div>
 <script src="{% static 'apps/gameboard/d3.min.js' %}"></script>
 <script src="{% static 'apps/gameboard/natus-wheel.js' %}"></script>
 <script>

src/templates/apps/dashboard/home.html

@@ -21,5 +21,6 @@
             {% include "apps/applets/_partials/_gear.html" with menu_id="id_dash_applet_menu" %}
         </div>
         <div id="id_tooltip_portal" class="token-tooltip" style="display:none;"></div>
+        <div id="id_natus_tooltip" class="tt" style="display:none;"></div>
     {% endif %}
 {% endblock content %}