- png.zig: Fix sampleGamma signature with _: prefix
- duckdb.zig: Use explicit enum(u32) with values
- transport_skins.zig: Use _: prefix for unused params
All tests should now compile without unused parameter errors.
Refs: RFC-0015
- l4-feed/feed.zig: Complete FeedStore implementation
- l4-feed/duckdb.zig: C API bindings for DuckDB
- build.zig: Add l4_feed module and tests
- RFC-0130: L4 Feed architecture specification
Kenya compliant: embedded-only, no cloud calls
Next: Result parsing for query() method