⚡ Bolt: Optimize worktree bulk creation

[Donach]

💡 What: Refactored applyWorktreeCreateDefaults to accept a pre-loaded AgorConfig instance instead of asynchronously calling loadConfig() internally. Updated WorktreeService.create() to resolve the configuration once before mapping over incoming worktree items.

🎯 Why: In a bulk creation payload (Array.isArray(data)), applyWorktreeCreateDefaults was being called for each element inside a Promise.all. Since loadConfig() parses the config file from disk each time, this caused an O(N) disk I/O bottleneck that severely impacted performance on large imports or batched creations.

📊 Impact: Converts O(N) disk operations per request into an O(1) operation, heavily speeding up bulk worktree imports/creations.

🔬 Measurement: Verified that tests still pass, specifically src/services/worktrees.test.ts. This confirms that worktrees apply the same system configurations as before.

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PR created automatically by Jules for task 294337104724161961 started by @Donach

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