feat: SQL syntax highlighting for iOS query editor

[datlechin]

Summary

• SQL syntax highlighting in the iOS query editor via UITextView + NSTextStorageDelegate
• Colors: keywords (blue), strings (red), numbers (orange), comments (gray), functions (purple)
• Incremental highlighting on each keystroke (line-boundary expansion, not full rescan)
• 10K character cap for performance
• Protected ranges: keywords inside strings/comments are not colored
• Dark mode compatible (UIColor semantic colors)

Architecture

• SQLSyntaxHighlighter: stateless enum with pre-compiled regex patterns
• SQLHighlightTextView: UIViewRepresentable wrapping UITextView
• NSTextStorageDelegate fires on character edits with exact edited range
• beginEditing/endEditing for batched attribute changes

Test plan

• Type SELECT * FROM users WHERE id = 1 - keywords blue, number orange
• Type 'hello world' - string red
• Type -- comment - gray
• Type /* block */ - gray
• 'SELECT' inside string stays red (not blue)
• Paste large SQL (>10K) - no freeze
• Dark mode - colors adapt
• Cursor, undo, copy/paste all work