Expose inverse, strikethrough, faint, invisible and cursor visibility in snapshot cells #15

Request

Expose the remaining SGR cell attributes and the cursor visibility mode in snapshot() output:

• SnapshotCell: inverse (SGR 7), strikethrough (SGR 9), faint (SGR 2), invisible (SGR 8).
• TerminalSnapshot: cursor visibility (DECTCEM, ESC[?25h / ESC[?25l), for example cursorVisible: boolean.

Why

agent-tty (coder/agent-tty) replays recordings through snapshot({ includeCells: true }) to export deterministic SVG without a browser (coder/agent-tty#171). In 0.1.0-beta.0, SnapshotCell (dist/types.d.ts) exposes only bold, italic, underline, foreground and background. TerminalSnapshot has cursorRow and cursorCol but no visibility flag. As a result:

• Reverse-video, strikethrough, dim and hidden text render as plain text. Reverse video matters most: TUIs use it for selection bars, status lines and fuzzy-finder highlights (fzf, htop, less).
• The cursor is always drawn, even after an application hides it with ESC[?25l.

Suggested shape

Optional booleans, following the existing bold?/italic?/underline? convention, so current consumers keep working:

export interface SnapshotCell {
  // existing fields...
  inverse?: boolean;
  strikethrough?: boolean;
  faint?: boolean;
  invisible?: boolean;
}
export interface TerminalSnapshot {
  // existing fields...
  cursorVisible?: boolean;
}

Report inverse as the raw attribute rather than pre-swapping foreground and background, so consumers can apply their own default colors. Once this ships, agent-tty can map the fields in its native backend (src/renderer/libghosttyVt/backend.ts) and SVG renderer (src/export/svg.ts), which already honors an optional cursorVisible flag.

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