chore(sandbox): bump to 0.5.5 + align sandbox-env chart image tag

[tlgimenes]

What is this contribution about?

Releases a new `studio-sandbox` image (`0.5.5`) and bumps the `sandbox-env` Helm chart so warm-pool sandboxes pick up the dual-serve daemon routes shipped in #3463 (`/_sandbox/` + legacy `/_decopilot_vm/`).

Without this bump, post-rename mesh (staging is already on `2.347.0`/`2.348.0`) calls `POST /_sandbox/config` against deployed `studio-sandbox:0.5.4` daemons that only know the legacy prefix, so the request falls through to the daemon's catch-all proxy and returns `503 "No dev server running"` HTML — sandboxes cannot start.

How to Test

1. Wait for the `release-studio-sandbox` workflow to publish `ghcr.io/decocms/studio/studio-sandbox:0.5.5`.
2. Sync the `sandbox-env` chart in staging (and prod).
3. `kubectl -n agent-sandbox-system delete pod -l app.kubernetes.io/name=studio-sandbox-stg` (and `-prod`) to recycle the warm pool onto `0.5.5`.
4. Open a sandbox preview from staging mesh — expected: dev server boots normally instead of the `503` "No dev server" page.

Migration Notes

Chart version bumped to `0.7.3`; `appVersion` and `image.tag` aligned to `0.5.5`. Deploys must roll the chart out before the warm-pool pods will use the new image.

Review Checklist

• PR title is clear and descriptive
• Changes are tested and working (post-deploy verification needed)
• Documentation is updated (if needed)
• No breaking changes

---

Summary by cubic

Release studio-sandbox 0.5.5 and align the sandbox-env chart so warm‑pool sandboxes pull the new image with dual-serve routes (/_sandbox/* + legacy /_decopilot_vm/*). This prevents 503s when the mesh calls POST /_sandbox/config.

• Dependencies

  • Bump @decocms/sandbox to 0.5.5; sandbox-env chart to 0.7.3; set appVersion and image.tag to 0.5.5.

• Migration

  • Roll out the updated sandbox-env chart to staging and prod.
  • Recycle warm‑pool pods to pull 0.5.5 and apply the change.

^{Written for commit fccbdc5. Summary will update on new commits. Review in cubic}

[github-actions]

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Should we run the Virtual MCP strategy benchmark for this PR?

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[github-actions]

Release Options

Suggested: Patch (2.348.1) — based on chore: prefix

React with an emoji to override the release type:

Reaction	Type	Next Version
👍	Prerelease	2.348.1-alpha.1
🎉	Patch	2.348.1
❤️	Minor	2.349.0
🚀	Major	3.0.0

Current version: 2.348.0

Note: If multiple reactions exist, the smallest bump wins. If no reactions, the suggested bump is used (default: patch).

[cubic-dev-ai]

No issues found across 3 files

_{Re-trigger cubic}