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/static/tests/SpecRunner.html

@@ -25,7 +25,7 @@
     <script src="SigSelectSpec.js"></script>
     <script src="SeaDealSpec.js"></script>
     <script src="FanStageSpec.js"></script>
-    <script src="NatusWheelSpec.js"></script>
+    <script src="SkyWheelSpec.js"></script>
     <script src="NoteSpec.js"></script>
     <script src="NotePageSpec.js"></script>
     <!-- src files -->
@@ -40,7 +40,7 @@
     <script src="/static/apps/epic/sea.js"></script>
     <script src="/static/apps/gameboard/game-kit.js"></script>
     <script src="/static/apps/gameboard/d3.min.js"></script>
-    <script src="/static/apps/gameboard/natus-wheel.js"></script>
+    <script src="/static/apps/gameboard/sky-wheel.js"></script>
     <!-- Jasmine env config (optional) -->
     <script src="lib/jasmine-6.0.1/boot1.js"></script>