rename natus → sky across the codebase — natal chart abstraction is now sky throughout, since chart inputs aren't birthday-gated

Mechanical rename: 5 files (sky-wheel.js, _sky.scss, _sky_overlay.html, SkyWheelSpec.js x2), 24 in-place edits across templates/views/urls/SCSS/JS/tests/CLAUDE.md. URL names epic:natus_save → epic:sky_save (epic namespaced, no clash w. dashboard:sky_save), JS module NatusWheel → SkyWheel, DOM ids id_natus_* → id_sky_*, BEM classes natus-* → sky-*, dashboard sky_natus_data/sky_natus_preview collapsed to sky_data/sky_preview_data. No DB migration needed (User.sky_chart_data + GameEvent.SKY_SAVED already used sky-prefix). 778 ITs + Jasmine green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/templates/apps/dashboard/home.html

@@ -21,7 +21,7 @@
             {% 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>
-        <div id="id_natus_tooltip_2" class="tt" style="display:none;"></div>
+        <div id="id_sky_tooltip" class="tt" style="display:none;"></div>
+        <div id="id_sky_tooltip_2" class="tt" style="display:none;"></div>
     {% endif %}
 {% endblock content %}