🧹 [Code Health] Reduce deep nesting in extract_comments

[Tcode-Motion]

🎯 What: Extracted the symbol name extraction logic in DocExtractor::extract_comments into a helper function extract_symbol_name. Also utilized a continue early return to skip subsequent processing on /// comment lines.
💡 Why: The original code had heavily nested if statements that made the main loop in extract_comments very difficult to read. By pulling out the symbol name slicing logic into a dedicated helper function, and using early returns, the main function is much cleaner, flat, and easier to follow.
✅ Verification: Ran cargo test -p techscript_package_manager to confirm all 8 local tests passed, ensuring identical behavior. Also ran the full workspace test suite cargo test --workspace to verify there were no regressions elsewhere.
✨ Result: A significant improvement in the maintainability and readability of DocExtractor::extract_comments by eliminating multiple levels of indentation, with zero change in the external behavior.

---

PR created automatically by Jules for task 17299272704018564273 started by @Tcode-Motion

[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.