⚡ Refactor TextUtils to use static Regex instances

[Aatricks]

💡 What: Extracted repeatedly compiled regular expressions within TextUtils.kt (such as those in removeCommonJunk, removeChapterMarkers, cleanSeparators, extractChapterLabel, extractChapterLabelFromUrl, and cleanChapterTitle) out of their functions and into static private val properties at the singleton object level.

🎯 Why: To improve text processing performance by parsing and compiling regex strings only once instead of every single time a method is invoked. This directly addresses the problem described in TextUtils.removeCommonJunk and applies the same optimization pattern globally within the file for maximum gain.

📊 Measured Improvement: Created a new benchmark class TextUtilsBenchmarkTest to quantify the difference across 50,000 iterations.

• extractBaseTitle (which heavily utilizes removeCommonJunk): ~1782ms (baseline) ➔ ~1195ms (optimized), showing an approximate 33% improvement.
• extractChapterLabel: ~143ms (baseline) ➔ ~124ms (optimized), showing a more modest but consistent 13% improvement.

All text manipulation logic and existing test coverage remain exactly the same.

---

PR created automatically by Jules for task 13404907790383770220 started by @Aatricks

[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.