fix: report partial DNS inspection failures

[ryanfowler]

Summary

• preserve successful DNS records when an explicit resolver has partial query failures
• warn with affected record types and query errors, and return exit code 1
• retain UDP truncation fallback warning behavior
• document partial-failure semantics

Validation

• cargo fmt --check
• cargo clippy --locked --all-targets --all-features -- -D warnings
• cargo test --locked --all-features --lib --bins
• cargo test --locked --all-features --test cli --test formatting --test grpc --test har --test http --test install --test network --test terminal --test update --test websocket -- --test-threads=2

The first full unit run had one unrelated flaky QUIC cleanup failure; the isolated rerun passed.