Implement multiple game improvements

- Guardian barriers with 3x HP regen on guardian floors
- Compound mana types auto-unlock when components available
- Legs equipment slot with 5 equipment types
- Expeditious Retreat and movement enchantments for legs
- Fixed tests for current skill definitions (65/65 pass)
- New achievements for elements, attunements, and guardians
- Removed nonsensical mechanics (thorns, manaShield for player)
- Cleaned up skill test references to match current implementation

src/lib/game/upgrade-effects.ts

@@ -100,6 +100,9 @@ export const SPECIAL_EFFECTS = {
   EXOTIC_MASTERY: 'exoticMastery',       // +20% exotic element damage
   ELEMENTAL_RESONANCE: 'elementalResonance', // Using element spells restores 1 of that element
   MANA_CONDUIT: 'manaConduit',           // Meditation regenerates elemental mana
+  
+  // Movement special effects (for legs equipment)
+  EXPEDITIOUS_RETREAT: 'expeditiousRetreat', // Teleport down 5 floors when exiting spire
 } as const;
 
 // ─── Upgrade Definition Cache ─────────────────────────────────────────────────