Fix staking unbonding period display: correct era to days conversion

- Changed warning message calculation from ~{bondingDuration} days to ~{Math.floor(bondingDuration / 4)} days
- Correct conversion: 4 eras = 1 day (1 era = 6 hours)
- Example: 112 eras now correctly shows as ~28 days instead of ~112 days
- Location: src/components/staking/StakingDashboard.tsx:661

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

src/components/staking/StakingDashboard.tsx

@@ -658,7 +658,7 @@ export const StakingDashboard: React.FC = () => {
               <Alert className="bg-yellow-900/20 border-yellow-500">
                 <AlertCircle className="h-4 w-4" />
                 <AlertDescription className="text-sm">
-                  Unbonded tokens will be locked for {bondingDuration} eras (~{bondingDuration} days) before withdrawal.
+                  Unbonded tokens will be locked for {bondingDuration} eras (~{Math.floor(bondingDuration / 4)} days) before withdrawal.
                 </AlertDescription>
               </Alert>