🌱 Add structured CI-observability summary to fuzz-mdx harness

[kubestellar-hive]

Fixes #6770

What

fuzz-mdx-sanitizer.ts (the harness behind fuzz-mdx.yml) only printed decorative free-text lines (PASSED: all N iterations clean corpus=M / FAILED: K violation(s) found) to stdout. There was no machine-readable summary and no record of the run's outcome visible without opening the raw job log.

Change

At the end of the same run (both pass and fail paths), the harness now:

• Prints one bounded FUZZ_MDX_SUMMARY JSON line (fixed fields only: status, seed, iterations, corpus_size, failures — no test inputs, error text, or unbounded content).
• Appends a short Markdown table to $GITHUB_STEP_SUMMARY when that env var is set, so the run's outcome renders in the GitHub Actions run summary UI without opening raw logs.

This happens in-process, before process.exit(), on both the pass and fail branches — so it covers both outcomes without needing a separate workflow step or if: always() wiring, and requires no workflow YAML changes.

Verification

• Ran the harness locally with GITHUB_STEP_SUMMARY set: confirmed the Markdown table is appended on a passing run.
• Ran with the env var unset (matches local/dev usage): confirmed no crash, unchanged existing stdout output.
• npx eslint and npx tsc --noEmit -p tsconfig.json: no new errors (same pre-existing no-console warnings as before, matching the file's existing baseline).

Out of scope

No metrics backend, exporter, or off-box data flow — CI-log/UI observability only, consistent with the 'no backend confirmed' posture for this repo. No new dependency (uses node:fs, already available).

— hive: agent=telemetry backend=copilot model=claude-sonnet-4-6

[kubestellar-hive]

Important

Held for human sign-off on the direction, not on the code.

This PR's only tracked rationale is #6770, which the hive filed itself — issue #6770 was filed by kubestellar-hive[bot] and no human has acknowledged it. An agent-filed issue does not, on its own, establish that anyone agreed to the direction (hivecommons/hive#5117).

The change may well be right; nothing here is a review of it. To release the hold, acknowledge the direction on that issue — comment on it, assign yourself, or add the approved-direction label — and remove the hold label here.

[kubestellar-prow]

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[kubestellar-prow]

Hi @kubestellar-hive[bot]. Thanks for your PR.

I'm waiting for a kubestellar member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Details

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