PICK SKY: natal wheel icon + palette sprint — inline SVG zodiac icons, per-planet alchemical colors

- Replace Unicode glyph text elements with inline SVG <path> icons loaded from icons/zodiac-signs/*.svg files
- NatusWheel.preload() fetches + caches all 12 zodiac SVG paths before first draw; auto-detects static base URL from <script src>
- Per-element (fire/stone/air/water) colored circles behind zodiac icons; icon fill colors use element palette vars
- PLANET_ELEMENTS map (au/ag/hg/cu/fe/sn/pb/u/np/pu) drives per-planet circle + label CSS modifier classes
- Planet circles: ternary fill + senary stroke per alchemical metal palette; labels: senary fill + stroke halo
- Zodiac icon scale = 85% of circle diameter (15% inset so icons breathe inside circles)
- Zodiac + house segment bg opacity 0.5; all ring/segment borders --terUser

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

src/templates/apps/gameboard/_partials/_natus_overlay.html

@@ -130,6 +130,10 @@
   const PLACE_DELAY   = 400;   // ms — Nominatim polite rate
   const CHART_DELAY   = 300;   // ms — chart preview debounce
 
+  // Preload zodiac SVG icons eagerly — they'll be cached before any draw() call.
+  // To swap an icon, replace the .svg file in zodiac-signs/ and hard-refresh.
+  NatusWheel.preload();
+
   // ── localStorage persistence ──────────────────────────────────────────────
   // Key scoped to room so multiple rooms don't clobber each other.