Add Mermaid diagrams to visualize the trait hierarchy, compact int storage layout, and SIMD-vectorizable arithmetic operations for MemoryIntVec and PersistentCompactIntVec. Also document concrete type structures and planned layer/partition composition rules to improve documentation clarity.
Document the two-tier compact integer encoding, BitSlice/IntSlice trait hierarchy, and SIMD-friendly O(n+k) algorithms. Include details on concrete memory and persistent vector types, matrix aggregation traits, and planned group-filtering APIs.