fix: JSONC comment stripping now respects string boundaries

The naive regex /\/\/.*$/gm was incorrectly stripping content after
// inside string values (like URLs). This caused config files with
http:// or https:// URLs to become malformed JSON.

Added a proper state-machine based JSONC stripper that:
- Tracks string boundaries
- Handles escaped quotes
- Preserves // and /* inside quoted strings
- Only strips actual comments outside strings

Fixes #11