Show unavailable route distance without numeric overflow

[timohueser]

An unreadable route can report no cross-track distance. Map and Statistics previously formatted its u32::MAX sentinel as a number, which overflowed in checked builds and produced false output in release builds. They now show their existing off-route label without a numeric distance.

Distance rounding uses wider intermediate values. The compact distance buffer and its two transient stat-cell consumers hold the complete u32-range result, including its unit. Normal thresholds, rounding, translations and navigation policy are unchanged. No resident App field changes.

Closes #1722. Parent #1433; program #1448. The original trace came from a truncated browser card followed by replay seek during #1720; its narrower reset checks remain intact.

Validation:

• Independent source review approved e15c7c06 with no findings. Clean rebase onto80241949 preserved both patches exactly; final head e8534d6.
• CARGO_INCREMENTAL=0 CARGO_TARGET_DIR=/Users/timo/Documents/OSM/target ./tools/obc test -p obc-app -p obc-route: 1,371 passed (App1,152 unit/integration+4 doc; route215),4 existing ignored doc examples. Real empty/unreadable route sources pass through Navigator to both rendered screens in metric/imperial; text rows match label-only chrome. Formatter maxima and normal crossover cases pass.
• Registry69 suites/350 units, affected plan29/69, all four Cargo-root formatting checks and diff check passed.
• cargo clippy --locked -p obc-app -p obc-route --all-targets --all-features -- -D warnings: passed. cargo check --locked -p obc-app -p obc-route --no-default-features --target thumbv8m.main-none-eabihf and cargo build --locked -p obc-sim --bin obc-sim also passed. Only normal Map/Statistics frames were rendered; both match their existing manifest hashes.
• One final shipping image on the combined head passes strict alignment and all resource limits. Linked resident312,952 B; arena131,072 B; residual stack46,472 B; guarded poll9,952 B; task4,048 B; boot chain16,688 B. Named frame maxima: init72 B, storageflat10,264 B, boardflat9,344 B. ELF SHA-256 f5e128e95057d3d3ca3928ebbc8f188ce44a55c3fa8e414c026a16f687f05c1b. This includes independently merged Peak View storage changes; this PR changes no resource baseline or ceiling. The selected direct planning chain is40,792 B including common prefix, leaving5,680 B before interrupt/other indirect costs. Physical high-water remains unmeasured on this image.

No public documentation changes: this corrects an error label and bounds arithmetic, with no new strings or normal behavior. No full local snapshot/workspace sweep, external fixture download, base/diagnostic firmware build or physical test. CI covers wider consumers.

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 5ddc6046-f08f-4705-916b-75251781d2b1

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}