Adds the kb-parse-types crate per design §3.7b. Depends only on kb-core
+ serde/thiserror — never on parser libraries. Defines:
- ParsedBlock + ParsedBlockKind + ParsedPayload (8 variants matching
Block variants in kb-core).
- Warning + WarningKind for parser diagnostics.
- Forward-declared ParsedImageRegion / ParsedPdfPage / ParsedAudioSegment
shells for P6/P7/P8.
`cargo tree -p kb-parse-types` shows only kb-core, serde, and thiserror.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
altair823
030986b37c