feat(earth): toolbar zoom improvements and toggle-cables

- Remove zoom slider, implement click/hold zoom behavior (+/- buttons)
- Add 10% step on click, 1% continuous on hold
- Add box-sizing/padding normalization to toolbar buttons
- Add toggle-cables functionality with visibility state
- Fix breathing effect: faster pulse (0.008), wider opacity range (0.2-1.0)
- Fix slider null error in updateZoomDisplay
- Set satellite default to hidden

frontend/public/earth/js/constants.js

@@ -39,11 +39,11 @@ export const CABLE_COLORS = {
 };
 
 export const CABLE_CONFIG = {
-  lockedOpacityMin: 0.6,
+  lockedOpacityMin: 0.2,
   lockedOpacityMax: 1.0,
   otherOpacity: 0.5,
   otherBrightness: 0.6,
-  pulseSpeed: 0.003,
+  pulseSpeed: 0.008,
   pulseCoefficient: 0.4
 };