feat(ontology): implement Dynamic Ontology multi-agent workflow

Add complete Dynamic Ontology pipeline following Akash Goyal's approach:
- Two-layer architecture: curated schema + ontology catalog
- Coverage governance signal for quality tracking
- Grounding metadata for normalized terms
- Specialized agents: Extraction, Normalization, Coverage, Review
- Uses LeadWithSpecialists workflow pattern

Files:
- dynamic_ontology_config.json: Role configuration with 6 agents
- ontology_workflow.rs: Complete workflow implementation
- lib.rs: Added grounding metadata types (EntityType, RelationshipType,
  ExtractedEntity, SchemaSignal, CoverageSignal, GroundingMetadata)

Uses existing fuzzy matching (Levenshtein/Jaro-Winkler) instead of
vector embeddings - matches article's approach without new dependencies.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Terraphim CI

crates/terraphim_multi_agent/src/workflows/mod.rs

@@ -0,0 +1,3 @@
+//! Workflows module
+
+pub mod ontology_workflow;