Add missing security.yml workflow blocking all PR merges

[Copilot]

Branch protection requires a "Security Scan" workflow that doesn't exist in the repository, blocking all PRs with mergeable_state: "blocked" and 0 status checks.

Changes

• .github/workflows/security.yml - Security scan workflow using Safety (dependency vulnerabilities) and Bandit (code security linting)
• SOLUTION_INSTRUCTIONS.md - Administrator guide with 3 fix options
• MERGE_BLOCK_ANALYSIS.md - Technical analysis and evidence

Evidence

• GitHub API shows workflow ID 221404574 exists (created 2026-01-07)
• Workflow file never committed to any branch (verified git history)
• PR Fix task failure handling when task is not a Signature #56 CI runs succeed, but merge blocked waiting for Security Scan
• Status endpoint returns total_count: 0 - no checks reporting

Deployment

This PR cannot self-merge. Administrator must either:

1. Remove "Security Scan" from required checks → merge this PR → re-enable check
2. Push security.yml directly to main/develop branches (see instructions)
3. Use admin override to bypass branch protection

Once deployed, all blocked PRs become immediately mergeable.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/imaginary-cherry/mageflow/commits/489471d85783e2c55af7150a79e8ae6af23476e0/check-runs
  • Triggering command: /usr/bin/curl curl -s -H Accept: application/vnd.github+json REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.