fix: preserve cursor styles in captures

[opencode-agent]

Summary

• preserve Ghostty cursor style in structured terminal frames
• render block, hollow, underline, and bar cursors with distinct SVG/PNG geometry
• update cursor-only frame changes even when no terminal cells are dirty
• introduce frame v2 and driver protocol v2, with matching TypeScript client types and release changeset

Validation

• cargo fmt --all -- --check
• cargo test --all-targets -- --test-threads=1 (154 passed, 1 ignored)
• cargo clippy --all-targets --all-features -- -D warnings
• cargo build --release
• bun run test:npm
• bun run build:npm
• node scripts/validate-npm-packages.mjs with Node 22
• cargo package --list
• cargo package
• manually captured OpenCode block, line, and underline cursor configurations as distinct PNG shapes

Requested by: @rekram1-node (Aiden Cline via Slack)