Restore per-row results for polled submissions

[msaroufim]

Summary

• parse optional persisted run results returned by KernelBot polling
• render ordered per-row output for test and benchmark submissions
• retain background polling for test, benchmark, and leaderboard durability; native profile remains on SSE
• preserve queue updates, leaderboard geomean output, and secret-validation failure handling
• fall back to the existing summary when talking to an older server

Root cause

The background submission migration made jobs resilient to client disconnects, but the polling response omitted the detailed result map used to render individual rows. Returning to SSE would restore rows while reintroducing cancellation on disconnect.

Backend dependency

Requires gpu-mode/kernelbot#511. That API change is additive and exposes results only for non-secret test/benchmark runs. This client also filters secret runs defensively.

Validation

• cargo fmt --all -- --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test (45 passed)
• mock HTTP regression covering background test/benchmark/leaderboard routes, row rendering, and profile SSE

Kernelboard is unaffected: it uses the unchanged submission POST contract and does not consume the owner-only submission-details endpoint.