Fix recipe-run live timeout diagnostics

[chubes4]

Summary

• Add a bounded live recipe-run watchdog with a default 25 minute budget and optional --timeout override.
• Emit structured timeout failures with the active operation, elapsed time, timeout budget, artifacts, and run-registry failure metadata.
• Avoid timeout cleanup hangs by marking destroyed Playground runtimes before disposal and keeping artifact preview metadata from re-booting destroyed runtimes.
• Add a timeout smoke that deliberately stalls a live PHP operation, verifies JSON diagnostics/artifact logs, and checks no matching recipe-run process remains.

Closes #503.

Testing

• npm run build
• npm run recipe-run-timeout-smoke
• npm run recipe-playground-boot-failure-smoke
• npm run recipe-interruption-artifacts-smoke
• npm run recipe-runtime-evidence-smoke
• npm run recipe-dry-run-smoke
• npm run browser-probe-artifact-smoke
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Investigated the recipe-run timeout path, drafted and implemented the watchdog/cleanup changes, added regression smoke coverage, and ran targeted verification.