Redesign skill system around attunements

- Add attunementLevel field to SkillDef type
- Organize skills into Core, Enchanter, Invoker, and Fabricator trees
- Core skills (mana, study, ascension) available to all players
- Enchanter skills require Enchanter attunement and scale with level
- Invoker skills for pact mastery and invocation (requires Invoker attunement)
- Fabricator skills for golemancy and fabrication (requires Fabricator attunement)
- Add attunement level requirements for advanced skills (Lv 3, 5, 7, 8)
- Update SkillsTab UI to show attunement requirements
- Update store to validate attunement requirements before studying

src/components/game/tabs/SkillsTab.tsx

@@ -186,6 +186,21 @@ export function SkillsTab({ store }: SkillsTabProps) {
                   const tierDef = SKILL_EVOLUTION_PATHS[id]?.tiers.find(t => t.tier === currentTier);
                   const skillDisplayName = tierDef?.name || def.name;
                   
+                  // Check attunement requirements
+                  let attunementMet = true;
+                  let attunementReqText = '';
+                  if (def.attunement) {
+                    const attState = store.attunements?.[def.attunement];
+                    const requiredLevel = def.attunementLevel || 1;
+                    if (!attState?.active) {
+                      attunementMet = false;
+                      attunementReqText = `Requires ${def.attunement.charAt(0).toUpperCase() + def.attunement.slice(1)} attunement`;
+                    } else if ((attState.level || 1) < requiredLevel) {
+                      attunementMet = false;
+                      attunementReqText = `Requires ${def.attunement.charAt(0).toUpperCase() + def.attunement.slice(1)} Lv.${requiredLevel}`;
+                    }
+                  }
+                  
                   // Check prerequisites
                   let prereqMet = true;
                   if (def.req) {
@@ -212,7 +227,7 @@ export function SkillsTab({ store }: SkillsTabProps) {
                   const cost = Math.floor(baseCost * costMult);
                   
                   // Can start studying?
-                  const canStudy = !maxed && prereqMet && store.rawMana >= cost && !isStudying;
+                  const canStudy = !maxed && attunementMet && prereqMet && store.rawMana >= cost && !isStudying;
                   
                   // Check for milestone upgrades
                   const milestoneInfo = hasMilestoneUpgrade(tieredSkillId, level, store.skillTiers || {}, store.skillUpgrades);
@@ -254,6 +269,11 @@ export function SkillsTab({ store }: SkillsTabProps) {
                           )}
                         </div>
                         <div className="text-xs text-gray-400 italic">{def.desc}{currentTier > 1 && ` (Tier ${currentTier}: ${fmtDec(tierMultiplier, 0)}x effect)`}</div>
+                        {!attunementMet && attunementReqText && (
+                          <div className="text-xs text-orange-400 mt-1">
+                            🔒 {attunementReqText}
+                          </div>
+                        )}
                         {!prereqMet && def.req && (
                           <div className="text-xs text-red-400 mt-1">
                             Requires: {Object.entries(def.req).map(([r, rl]) => `${SKILLS_DEF[r]?.name} Lv.${rl}`).join(', ')}