Add toggle to disable auto-collapse of pasted text

Description

When pasting long text into the Claude Code CLI, it automatically collapses to a summary like pasted text +XX lines. While this keeps the terminal clean, there are cases where seeing the full pasted content is important.

Proposal

• Option A: Boolean toggle: paste_collapse: false in settings
• Option B: Threshold: paste_collapse_threshold: 200 (lines)
• Option C: Keybinding/modifier to temporarily disable for a single paste

Use case

• Pasting full prompts or specifications verbatim
• Reviewing exactly what was pasted before submitting
• Pasting structured data (JSON, YAML, logs)