fix: treat missing native setup as doctor info

[AlainDor]

Summary

Treat completely missing project-local Claude/Codex native setup as informational in mimir doctor, while keeping partial setup actionable. This lets public repos that prohibit agent artifacts still reach green doctor readiness.

Track

transparent harness / adapters

Verification

• cargo fmt --all -- --check
• cargo build --workspace --all-features
• cargo test --workspace --all-features
• cargo clippy --all-targets --all-features -- -D warnings
• cargo deny check
• cargo doc --workspace --no-deps
• cargo test -p mimir-harness --test recovery_benchmark
• python3 benchmarks/recovery/test_bench.py
• cargo publish --dry-run -p mimir-core --allow-dirty
• cargo run -p mimir-harness -- doctor --project-root .

Notes

• mimir doctor now reports doctor_readiness=ready and doctor_action_count=0 for this workspace.
• No tracked agent artifacts are present.