regex: vpcre more optimizations 😄

[penguindark]

What's in

• added more optimizations:
  • Zero-Allocation Search: Reuses a pre-allocated Machine workspace for search operations.
  • Anchored Optimization: Patterns starting with '^' skip the scanning loop.
  • Prefix Skipping: Using Boyer-Moore-like skipping for literal prefixes.

Usage change

• use of a direct struct variable to change max_stack_depth (I prefer to avoid fn call for this, should be not a problem because the function was merged only yesterday.)
  r.change_stack_depth(4000) => r.max_stack_depth = 4000

AI support: Gemini pro 3 preview

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 01f66ac933

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

[spytheman]

Thank you @penguindark 🙇🏻 .