fix: improve preflight e2e daemon readiness diagnostics

[jverdicc]

Motivation

• The preflight e2e step was failing because the EvidenceOS daemon rarely responded at http://127.0.0.1:8787/preflight within the timeout, and failure logs were not immediately visible in the job output.
• Missing --data-dir parent directory can cause the daemon to crash on startup, so ensure the path exists before launching the daemon.
• Readiness can manifest on different endpoints (/preflight, /health, /), so broaden the probe to avoid false failures when a different route is served.

Description

• Create the explicit data directory before starting the daemon by adding mkdir -p artifacts/preflight-e2e/data in the workflow start step.
• Make readiness probing more resilient by checking /preflight, /health, and / for HTTP 200 during the 60-second warm-up loop and update the failure message accordingly.
• Add a post-failure workflow step that, when the job fails, prints artifacts/preflight-e2e/daemon.log, artifacts/preflight-e2e/daemon.pid, and a ps aux | grep evidenceos process listing to surface daemon startup diagnostics in the job log.

Testing

• Ran git diff --check -- .github/workflows/ci.yml and it completed with no warnings or whitespace errors.
• Full workflow/CI could not be executed in this environment because the pinned EvidenceOS repository could not be fetched due to outbound network restrictions, so end-to-end verification using the real daemon was not possible here.
• The change was committed to the repository and is ready for CI to run these improved diagnostics and readiness checks in the remote environment.

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Codex Task