Remove deprecated SyntaxParser API (parse(code:options:) and SyntaxResponse) #149

Context

PR #147 introduced SyntaxParser.parse(code:) returning [TreeNode] directly, and simultaneously deprecated parse(code:options:) and SyntaxResponse with messages pointing to the new API.

Both deprecated items are package-access only — they have no external callers that need a migration window.

Proposed Work

• Delete Sources/SyntaxParser/SyntaxResponse.swift
• Remove parse(code:options:) from Sources/SyntaxParser/SyntaxParser.swift
• Update any internal call sites (currently only skit executable)

This removes deprecation noise from a PR that already introduced the replacement.