feat(bashkit): Phase 4 - Here documents, builtins, and parameter expansion

[chaliy]

Summary

• Added here document support (<<EOF) with lexer heredoc parsing
• Added new builtins: set, unset, shift, local, source/.
• Implemented full parameter expansion with defaults, length, and pattern removal

Features

Here Documents

Supports heredoc syntax for multi-line input.

New Builtins

• set -e / set +e - shell options
• unset VAR - remove variables
• shift [n] - shift positional parameters
• local VAR=value - local variables in functions
• source file / . file - execute script from file

Parameter Expansion

• ${var:-default} use default if unset/empty
• ${var:=default} assign default if unset/empty
• ${var:+replacement} use replacement if set
• ${var:?error} error if unset/empty
• ${#var} length of value
• ${var#pattern} remove shortest prefix
• ${var##pattern} remove longest prefix
• ${var%pattern} remove shortest suffix
• ${var%%pattern} remove longest suffix

Test plan

• 100 tests passing
• Heredoc tests
• Parameter expansion tests
• New builtin tests
• Clippy clean

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, you can upgrade your account or add credits to your account and enable them for code reviews in your settings.