⚡ Bolt: [performance improvement] Cache loadConfig in bulk worktree creation

[Donach]

💡 What: Optimized applyWorktreeCreateDefaults to accept an optional preloadedConfig and hoisted await loadConfig() outside the data.map() loop in the bulk create method of the WorktreesService.

🎯 Why: loadConfig() reads and parses the YAML configuration file from disk. In bulk operations like passing an array of Worktrees into create, calling it within a map loop triggers $O(N)$ unnecessary disk I/O operations and synchronous parses.

📊 Impact: Reduces redundant filesystem access and parser overhead during bulk insertions from $O(N)$ to $O(1)$.

🔬 Measurement: Verified that unit tests in src/services/worktrees.test.ts continue to pass properly. Code formatting passes successfully.

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PR created automatically by Jules for task 2583908112253588636 started by @Donach

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