feat: Add coprus-report

[IsNeron]

Implemented the automated corpus reporting feature.
Key changes:

• Added corpus-report CLI command in main.rs.
• Added deterministic aggregation, text rendering, JSON serialization, and tests in corpus_report.rs
• Extended the existing specification model to retain scientific_notes and edge_cases in model.rs
• Documented usage and semantics in codegen/README.md and development.md

Usage:
cargo run --manifest-path codegen/Cargo.toml -- corpus-report
cargo run --manifest-path codegen/Cargo.toml -- corpus-report --format json
The JSON schema contains stable sources, functions, verification, inputs, outputs, scope, and blocked_functions sections. Frequency tables have explicit counts and percentages and deterministic ordering.
Current corpus results:

• 22 specifications/publications, covering 1972–2023
• 117 functions
• 113 implemented, 1 ready, 3 blocked, 0 draft
• 136 golden tests
• 19 declared edge cases

Verification passed:

• 81 codegen tests
• Rust formatting
• Clippy with warnings denied
• Strict documentation build
• Repeated JSON output comparison