[Feature Request] Add LaTeX/KaTeX math rendering to TUI

## Summary

The Claude Code terminal UI does not render LaTeX math. Inline ($...$) and display ($$...$$) expressions appear as raw text with
literal dollar signs and backslashes, making any math-heavy conversation unreadable in the CLI.

## Current Behavior

When Claude outputs:

```markdown
The DC component of a half-wave rectifier is $V_{DC} = \frac{V_m}{\pi} \approx 0.318\,V_m$.

$$V_{rms} = \sqrt{\frac{1}{T}\int_0^T v^2(t)\,dt}$$
```

The TUI displays it verbatim — $V_{DC} = \frac{V_m}{\pi}$ — instead of rendering the formula.

Screenshot of the issue:
(attach your screenshot here)

## Expected Behavior

Math expressions should render as readable formulas, either:

• As proper typeset math (via terminal graphics protocols), or
• As a Unicode fallback (e.g., V_DC = V_m / π ≈ 0.318·V_m).

## Use Case

I use Claude Code as a study companion for engineering coursework (electronics, signal processing, control systems). Claude
correctly produces well-formatted LaTeX from my lecture notes — but I can't read the output without copying it into an external
KaTeX renderer.

This affects anyone using Claude Code for:

• 📚 STEM coursework and tutoring
• 📄 Research papers (arXiv ML/CS/physics content)
• 📊 Math-heavy domains (DSP, finance, statistics, control theory)
• 🔬 Code review for numerical algorithms and ML loss functions

## Current Workarounds (all unsatisfactory)

| Workaround | Problem |
|------------|---------|
| Switch to claude.ai web | Lose project context, CLI tooling, MCP servers |
| Use VS Code with nuriyev.claude-code-katex extension | Forces me out of my preferred terminal workflow |
| Ask Claude to write formulas in ASCII/Unicode | Degrades fidelity — matrices, integrals, piecewise functions become ugly and
ambiguous |
| Pipe output to external math renderer | Breaks the interactive REPL experience |

## Proposed Solutions (in order of preference)

### 1. Native rendering via terminal graphics protocols
Render KaTeX/MathJax to PNG/SVG and display inline using:

• Kitty graphics protocol
• Sixel (xterm, foot, WezTerm, etc.)

Many modern terminals support at least one. Gracefully fall back to option 2 on unsupported terminals.

### 2. Unicode fallback renderer
Auto-convert common LaTeX patterns to Unicode math:

• \frac{a}{b} → a/b (or stacked Unicode where readable)
• \sqrt{x} → √x
• x_i, x^2 → xᵢ, x² (Unicode sub/superscripts)
• \int, \sum, \alpha, \pi → ∫, ∑, α, π
• \begin{cases}...\end{cases} → ASCII brace + indented lines

### 3. Opt-in external viewer
A setting like --math-renderer=browser that opens detected formulas in a local KaTeX preview, or copies them to clipboard as PNG.

## Related Issues

• #21433 (existing feature request for LaTeX rendering)

## Impact

For technical and scientific users, this is the single biggest blocker preventing adoption of Claude Code over claude.ai. The model
produces excellent math output — the rendering gap forces a UX downgrade that doesn't exist on the web.

## Environment

• Claude Code version: <your version, e.g., 1.0.151>
• Terminal: <e.g., kitty, alacritty, gnome-terminal>
• OS: <e.g., Arch Linux, macOS 14>
• Shell: <e.g., fish, zsh, bash>