Add security architecture pattern infospace

infospaces/patterns-of-it-securita-architecture/artifacts/entities/pattern-protected-main-branch.md

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+# Pattern: Protected Main Branch
+
+Status: seed
+Readiness target: RL2 private beta
+Primary owners: product repos, NetKingdom
+Genesis family: Supply chain
+
+## Problem
+
+Production code can be changed without review, tests, or traceable
+approval when the main branch is not protected.
+
+## Context
+
+Use this pattern for repositories that produce production services,
+platform manifests, policy packages, documentation standards, or release
+artifacts.
+
+## Forces
+
+- Teams need fast iteration.
+- Production branches need review and checks.
+- Emergency fixes need traceable override.
+- Branch rules should match artifact criticality.
+
+## Solution
+
+Protect main and release branches with review, required checks, signed
+or verified changes where useful, and explicit emergency override
+procedures.
+
+## Verification
+
+- Direct pushes to protected branches are blocked.
+- Required tests and reviews pass before merge.
+- Emergency overrides are logged and reviewed.
+- Release artifacts link back to protected branch commits.
+
+## Related Patterns
+
+- GitOps with Guardrails.
+- SLSA Build Provenance.
+- SBOM-per-Release.
+- Supply-Chain Provenance.