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_src/scss/_card-deck.scss

@@ -926,7 +926,7 @@ html:has(.sig-backdrop) {
 }
 
 // ── PICK SEA overlay ─────────────────────────────────────────────────────────
-// Mirrors .natus-* structure but with columns reversed:
+// Mirrors .sky-* structure but with columns reversed:
 //   left = transparent (Celtic Cross card positions)
 //   right = rgba(--priUser) opaque (spread select)
 
@@ -1414,7 +1414,7 @@ $_glow-gravity: 0 0 0.8rem 0.15rem rgba(var(--quaUser), 0.6);
 
 }
 
-// NVM button — same positioning as .natus-modal-wrap > .btn-cancel
+// NVM button — same positioning as .sky-modal-wrap > .btn-cancel
 .sea-modal-wrap > .btn-cancel {
     position: absolute;
     top: -1rem;