Polish chat TUI readability

[quick-ricon]

Summary

This PR turns the chat TUI into a more readable message surface:

• render message bodies through a small Python renderer package instead of the old jq | fold pipeline
• colorize TUI metadata, senders, mentions, and inline code spans while preserving stored chat text
• default the TUI to an 88-column, balanced-justified, padded card layout with metadata above the separator
• wrap bullets and numbered lists with hanging indents, including blank spacing between adjacent list items
• keep escape hatches for ragged text / old-ish layout: --no-justify, --justify-style greedy, --no-header-separator, --message-padding 0, --color never

Validation

• mise run test
• mise run readme -- --check
• mise exec -- codebase lint
• git pre-push returned WARN only because the local branch had no upstream before pushing; all five local commits have good Quick GPG signatures and the working tree was clean.

Notes

This intentionally does not include Ghostty/font integration. We discussed that as a future idea but punted it because it would either affect global Ghostty config or require a separate launcher/config integration.

[brownie-ricon]

Adversarial review: I found one real edge case in the list-continuation path.

Change request

• lib/tui/render/wrapping.py:283 treats any indented non-boundary line after a list item as a prose continuation of that list item. That works for hanging-indent wraps, but it also collapses deeper indented literal blocks/code examples into the bullet text. For example, a chat message like:

  - Here is output:
      indented code line should stay separate
      second line
  

  currently renders as:

  - Here  is  output:  indented code line should stay separate
    second line
  

  That is a regression from the old is_markdownish behavior for indented lines, and it hurts the TUI reading surface for exactly the common “bullet + pasted output/command block” shape.

  I opened fix-it PR #65 against this branch: #65

Stress tests performed

• Ran the full production-ish test path: mise run test.
• Ran generated docs/lint checks: mise run readme -- --check, mise exec -- codebase lint.
• Exercised the real TUI view task coverage already in test/tasks.bats, including --no-justify, --justify-style greedy, balanced justification, --no-header-separator, --message-padding 0, --color never, and NO_COLOR behavior.
• Manually rendered a bullet followed by deeper indented literal lines through lib/tui/render-messages; that exposed the collapse above.

Surviving concerns

• I did not find another blocker in the renderer split, ANSI reset/color handling, CLI escape hatches, or CI/non-TTY paths. The task-level tests do hit the actual chat tui:view --once/lib/tui/render-messages production path, not only helper internals, which is good.

Disposition

Requesting changes for the indented-block/list regression; #65 is the proposed fix. 🥐