Major gameplay improvements - barriers, HP regen, descent mechanic

- Fix transference mana display (show unlocked elements even with 0 mana)
- Remove blocking/dodging mechanics (player has no health):
  - Replace Seer's foresight with criticalMastery
  - Replace Warden's defensive skills with mana efficiency skills
  - Replace Strider's evasive with fluidMotion
- Add guardian barriers (50% of HP, doesn't regenerate)
- Add floor HP regeneration (scales with floor level, 0 for guardians)
- Implement climb-down mechanic:
  - Cannot switch away from climb while above floor 1
  - Must fight through each floor to exit
  - Exit Spire button triggers descent
- Update UI to show barrier bar and descent status

src/lib/game/attunements.ts

@@ -244,9 +244,9 @@ export const ATTUNEMENTS: Record<AttunementType, AttunementDef> = {
         base: 200,
         studyTime: 12,
       },
-      foresight: {
-        name: 'Foresight',
-        desc: 'Chance to anticipate and dodge attacks',
+      criticalMastery: {
+        name: 'Critical Mastery',
+        desc: 'Increased critical damage multiplier',
         cat: 'seer',
         max: 5,
         base: 250,
@@ -266,44 +266,44 @@ export const ATTUNEMENTS: Record<AttunementType, AttunementDef> = {
 
   // ═══════════════════════════════════════════════════════════════════════════
   // WARDEN - Back
-  // Protection and defense. Damage reduction and shields.
+  // Mana efficiency and resource management (no player health mechanics)
   // ═══════════════════════════════════════════════════════════════════════════
   warden: {
     id: 'warden',
     name: 'Warden',
     slot: 'back',
-    description: 'Shield yourself with protective wards and barriers.',
-    capability: 'Generate protective shields. -10% damage taken.',
+    description: 'Master the flow of mana. Reduce costs and extend your reserves.',
+    capability: 'Reduced mana costs. Extended mana reserves.',
     primaryManaType: 'barrier',
     rawManaRegen: 0.25,
     autoConvertRate: 0.12,
     icon: 'Shield',
     color: '#10B981',  // Green
     skills: {
-      warding: {
-        name: 'Warding',
-        desc: 'Generate protective shields',
+      manaEfficiency: {
+        name: 'Mana Efficiency',
+        desc: 'Reduced mana costs for all actions',
         cat: 'warden',
         max: 10,
         base: 100,
         studyTime: 8,
       },
-      fortitude: {
-        name: 'Fortitude',
-        desc: 'Reduce damage taken',
+      manaReserves: {
+        name: 'Mana Reserves',
+        desc: 'Increased max mana pool',
         cat: 'warden',
         max: 10,
         base: 150,
         studyTime: 10,
       },
-      reflection: {
-        name: 'Reflection',
-        desc: 'Chance to reflect damage to attacker',
+      manaRetention: {
+        name: 'Mana Retention',
+        desc: 'Reduced mana loss on loop reset',
         cat: 'warden',
         max: 5,
         base: 300,
         studyTime: 15,
-        req: { warding: 5 },
+        req: { manaEfficiency: 5 },
       },
       barrierMastery: {
         name: 'Barrier Mastery',
@@ -394,8 +394,8 @@ export const ATTUNEMENTS: Record<AttunementType, AttunementDef> = {
         studyTime: 8,
       },
       evasive: {
-        name: 'Evasive',
-        desc: 'Chance to avoid damage',
+        name: 'Fluid Motion',
+        desc: 'Increased combo duration before decay',
         cat: 'strider',
         max: 5,
         base: 200,