Expand feature matrix and add P7X tooling

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• expand the CLI/feature matrix with capability dimensions, missing portable commands, and ranked gap planning
• add portable standalone PKCS#7/P7X support with inspect-pkcs7 and extract-pkcx-pkcs7
• add tests that cover PKCX unwrap/inspection and prevent portable CLI matrix drift

Validation

• cargo fmt --all
• cargo test --test cli_pe_digest inspect_pkcs7 --locked
• cargo test --test cli_pe_digest extract_pkcx --locked
• cargo test --test cli_matrix_docs --locked
• cargo clippy --workspace --all-targets --locked
• cargo test --workspace --locked