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/_tooltips.scss

@@ -1,6 +1,6 @@
 // ── Tooltip base styles ───────────────────────────────────────────────────────
-// Shared by wallet tokens, game-kit kit bag, and natus wheel tooltips.
-// Portal tooltips (#id_tooltip_portal, #id_natus_tooltip) are position:fixed
+// Shared by wallet tokens, game-kit kit bag, and sky wheel tooltips.
+// Portal tooltips (#id_tooltip_portal, #id_sky_tooltip) are position:fixed
 // and override z-index; inline .tt cards use position:absolute within their
 // parent token container.