⚡ Bolt: Optimize DOM updates and element reuse in PlayerList

[SoftMissT]

💡 What:

• Batched className updates into a single string assignment instead of multiple classList.add()/remove() calls per latency tick.
• Reused existing Text and <em> DOM child nodes in PlayerList.updateLatencyText instead of executing document.createElement('em') and wiping textContent on every update cycle.
• Updated makeLatencySpan to return null immediately if the target player element (.player-name) is not in the DOM, preventing orphaned <span> nodes.

🎯 Why:

• Periodically updating player latency for connected users created continuous object creation and GC overhead (document.createElement) and triggered multiple DOM layout/style recalculation steps per user element.

📊 Impact:

• Eliminates repeated DOM element allocation and garbage collection churn during latency refresh cycles.
• Reduces DOM class manipulation operations per user latency update.

🔬 Measurement:

• Ran npm test and npm run build (including type check and package validation for Foundry VTT v14). All checks passed.

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PR created automatically by Jules for task 14546696445244481961 started by @SoftMissT

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