feat(theme): add operator highlight to all themes - #448

Summary

This PR adds consistent support for both Operator (Vim syntax) and ["@operator"] (Tree-sitter) highlight groups across all 95 base46 themes.

Details

• The Issue: In many themes, operators (+, -, =, *, etc.) were missing explicit highlight definitions and fell back to base05 (the standard foreground text color), making code operators blend into standard text and appear monochrome.
• The Solution: Added both Operator (in polish_hl.syntax) and ["@operator"] (in polish_hl.treesitter) across all 95 themes.
• Color Selection: Operators are styled using theme-appropriate vibrant accent colors from M.base_30 (primarily cyan, as well as red, blue, nord_blue, orange, dark_purple, baby_pink, firered, etc. depending on each theme's specific design palette).
• Formatting: Formatted code using StyLua per .stylua.toml.

Verification

• Checked all 95 theme files with luac -p (0 syntax errors).
• Verified 100% coverage: 95/95 themes have both ["@operator"] (Tree-sitter) and Operator (Vim syntax).
• Successfully compiled all theme highlights with Neovim headless:

  nvim --headless -c "lua require('base46').compile()" -c "qa"

  The build finishes cleanly with zero compilation or bytecode errors.