[codex] raise Rust coverage above 90 percent

[stephenlclarke]

Summary

• add targeted coverage for validator, obfuscator, and FIX helper paths that were still under-covered
• exercise CLI info/message/tag/component handlers end to end so src/main.rs and display rendering paths are covered through real command flows
• add generator and pcap2fix tests for repo-root discovery, sensitive-tag generation, resync, overlap, overflow, and other edge cases

Why

SonarCloud coverage on main was still below the desired threshold because several non-streaming CLI paths, the sensitive-tag generator, and pcap2fix error branches had little or no test coverage.

Impact

• raises the Sonar-aligned Cobertura report to 92.21% overall Rust line coverage
• improves regression protection around dictionary browsing, FIX helper behavior, generated sensitive-tag output, and TCP FIX reassembly edge cases

Validation

• cargo test --workspace
• cargo clippy --workspace --all-targets -- -D warnings
• make coverage

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud