fix: stabilize armor IPPE PnP

[XiaoPengYouCode]

Summary

• add lightweight geometry stabilization before Rust IPPE consumes armor corners
• add pose sanity gates for finite values, depth range, forward-facing points, and reprojection RMSE
• skip rejected PnP armors instead of panicking, and mark the checklist item as aligned

Verification

• cargo fmt --all -- --check
• cargo clippy --locked --workspace --all-targets -- -D warnings
• cargo test --locked --workspace --all-targets
• git diff --check