Enhancement: TUI polish — syntax highlighting, collapsible output, progress viz

[Delqhi]

Enhancement: TUI Polish

Inspired by

Crush (Charmbracelet terminal aesthetics), Warp (Rust GPU-accelerated)

What it does

Improve TUI visual quality to match Crush/Warp level:

1. Better syntax highlighting — use glamour v2 with custom theme, proper language detection
2. Collapsible tool output — long tool outputs collapsed by default, expand on click
3. Progress visualization — animated progress bars for long-running tools (test, build, quality gate)
4. Diff viewer — inline diff rendering with +/- coloring
5. Markdown rendering — proper code block rendering with language tabs
6. Smooth animations — fade-in for new messages, slide for panes

Current state

• bubbletea v2 + lipgloss v2 + glamour v2 (already SOTA stack)
• Chat rendering split into 6 files (chat_render_*.go)
• Missing: collapsible output, progress bars, diff viewer

Priority: Low

Effort: Medium