semantic-curation: fix anchors, metadata, and relations across backend + specs
- Replace legacy @PURPOSE with @BRIEF across 241 files
- Add missing [C:N] complexity tiers to function contracts in core modules
- Fix tombstone contracts: add @STATUS DEPRECATED to 5 deprecated anchors
- Resolve 7 unresolved @RELATION edges in executor.py (DictionaryManager, TranslationPreview, etc.)
- Fix flat hierarchical IDs in 4 test files (22 test functions)
- Fix invalid tags/relations in logger.py (@ADR, @CONSEQUENCES, DISABLED_BY)
- Rebuild semantic index: 9,576 contracts, 4,742 edges, 0 parse warnings