Fork stable 0.111.0 with gpt-5.4 xhigh defaults

This release tracks upstream stable rust-v0.111.0 and carries the maintained fork defaults on commit fa3ae94ce0e997827639bab28d639dfd0baaa902.

Included in this cut:

• default model gpt-5.4
• reasoning effort xhigh
• verbosity high
• reasoning summaries detailed
• portable runtime cleanup removing the broken liblzma and libz dependency path from the forked debug binaries
• GitHub-facing docs, issue templates, PR template, and security/contribution guidance retargeted to this fork

Distribution model:

• no fork-specific npm package
• no fork-specific Homebrew cask
• GitHub provides the source archives for this tagged release
• the supported execution path for the fork remains building from source from codex-rs/