chore: Add meta config

[anurag-stepsecurity]

No description provided.

[claude]

Review

Reviewed the addition of .stepsecurity/meta.json.

✅ Valid JSON, and the field mapping checks out:

• maintained_action_name: step-security/claude-code-action/base-action correctly points at the base-action/ subdirectory (published as step-security/claude-code-base-action).
• upstream_full_repo_name: anthropics/claude-code-base-action matches that subdirectory's confirmed upstream.

Since this is a machine-managed tooling config with no executable code, there was nothing actionable for the performance/test-coverage/security reviewers. No blocking issues — LGTM.

One optional sanity-check for the author: this meta describes the base-action sub-action's upstream. If StepSecurity's sync tooling also expects the root action (step-security/claude-code-action, replacing anthropics/claude-code-action) to be tracked, that would need its own entry — otherwise this is complete as-is.