⚡ Bolt: [performance improvement] Optimize file stat call in srt processing

[Jandir]

💡 What: Replaced the double syscall pattern (exists() followed by stat()) with a single try-except OSError block around stat() in _init_md_processing (escriba.py). Added comments explaining the optimization.

🎯 Why: The codebase performance pattern memory explicitly flags that checking path.exists() before path.stat() is inefficient, as exists() makes a stat() call under the hood. Using a try-except OSError reduces filesystem syscalls by half. While seemingly small on a per-file basis, this aligns with Bolt's "every millisecond counts" philosophy for I/O-bound operations and fixes a potential TOCTOU race condition.

📊 Impact: Reduces filesystem I/O operations by 50% when verifying SRT files during the markdown generation initialization phase.

🔬 Measurement: Running the provided test suite (pytest tests/) shows all existing tests continue to pass correctly, confirming the try-except block correctly handles missing/unreadable files without regression.

---

PR created automatically by Jules for task 15279024112896731616 started by @Jandir

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.