fix(cli): explain deleted benchmark submission failures

[IsuraManchanayake]

Summary

• Explain before submission, in both the plain CLI and TUI preview, that reports previously deleted on the selected server cannot be re-submitted, including through Select all.
• Recognize HTTP 409 submission_deleted as Failed: previously deleted, with guidance to run a new benchmark. Local files remain unchanged.
• Continue attempting other valid reports. Keep successful uploads, preserve normal duplicate handling, and report the uploaded/duplicate/deleted counts with a nonzero exit when any selected report fails.
• Document permanent deletion. No re-upload checkbox, override, report-schema change, or BaseRT change.

Companion web change: https://github.com/basecompute/computearena/pull/66. Older CLI versions already display the server's explanatory error; this patch adds the advance warning and specific result label.

Verification

• cargo test --workspace --all-targets --quiet: 126 passed.
• cargo clippy --workspace --all-targets -- -D warnings: passed.
• cargo fmt --all -- --check: passed.
• Black-box test enters all in the actual saved-report picker, uses a loopback HTTP server returning deleted/success/duplicate results, checks nonzero exit and partial-success counts, and verifies local reports are unchanged. Also covers an all-deleted batch.
• TUI preview test asserts the deletion warning is present; API tests cover missing server error text and unrelated conflicts.
• Tests use synthetic runtimes/reports, not GPU benchmarks or production accounts.

Manual test

1. Against the companion web deployment, delete a disposable submitted benchmark, keeping its local signed report.
2. Select all saved benchmarks in the CLI and submit.
3. The deleted report must show Failed: previously deleted and explain that a new run is needed. Other valid reports should still submit; existing published reports should remain successful duplicates.
4. Check the final counts and verify local files are unchanged.

Targets the active rc-0.1.2 release candidate.