Fixed:
- CLI help typo: "metatdata" -> "metadata"
- Filter buffer OOM: check size before loading into memory
Changed:
- #[inline] on HTML escape helpers for hot path performance
- Replaced once_cell and lazy_static with std::sync::LazyLock
- Removed unused once_cell and lazy_static crate dependencies
Refactored:
- Added module-level doc to services/ module
Documentation:
- README.md: zstd is native not external, "none" -> "raw"
- DESIGN.md: current schema and meta plugins section
- CHANGELOG.md: Unreleased section populated
