feat(tui): color the bash tool's command as shell code - #54704

Note: I'm aware v1 is now the maintenance branch and new features go to v2 only. This PR is here for others to use, and I'll submit the v2 version once I've migrated my whole plugin system to it.

Issue for this PR

Closes #54700

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The bash tool's command is colored like write and edit already are. It is the same <text>$ command</text> as before with each token a colored span, so it wraps, indents and fits the block exactly as the plain command does; only the colors differ. It draws plain at once and takes its colors when the parser worker answers.

• util/highlight-cache.ts: a command asks for its colors every time its block is created, so a remounted transcript or reopened session would reparse every command. Results are cached by language and content (LRU, 1000 entries / 4M chars); identical concurrent requests share one round trip; a failure is retried.
• theme/tool-code.ts: red means a failed or rejected tool call in the transcript, so code inside a tool call never uses red. Every syntax slot that is red, or the theme's error color (builtins use it in every theme), takes a non-red alternative, e.g. variables and builtins take the function color.
• util/bash-highlight.ts: nvim-treesitter's bash query narrows its number, constant and shebang captures with #lua-match?, which web-tree-sitter does not evaluate, so every word came back as a number. Those patterns are applied after the worker answers. It also drops @spell, which the theme colors as plain text and which turned comments back to the text color.
• syntax.bash: false in tui.json restores the plain command. On by default. Documented in tui.mdx.

How did you verify your code works?

• bun typecheck in packages/tui; bun test test/util test/config.test.tsx test/cli/tui test/tool-code-theme.test.ts: 114 pass. shell-command.test.tsx renders a long command with long path tokens as spans and as plain text at 40, 80 and 160 columns and requires identical frames; tool-code-theme.test.ts checks every built-in theme, dark and light, for red or error-colored slots.
• A real TUI at 80 and 160 columns: the screen text with syntax.bash on and off is byte-identical.
• Real parser worker on real commands: for/in keywords, $HOME constant, numbers only on numbers.
• A real TUI on a copied 6,000-part session, through a PTY client on a throwaway tmux server, A/B/B/A against the same tree without the change: scroll p50 13.8 → 17.3 ms, keystroke p50 26.7 → 24.6 ms, idle CPU unchanged (run-to-run spread is larger than either difference).

Screenshots / recordings

Text capture (colors: cd/grep function, "$HOME" string, 10 number):

$ cd /tmp && ls -la | grep -v total; echo "$HOME" $((1 + 2)) && FOO=bar ./run.sh --flag 10

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

This PR is AI generated, but under direct supervision and on request of @Nowaker.