Agentic Workflow Guard v1.3.0

Adds Agent Context Guard with AWG012. AWGuard now scans persistent agent instruction files such as AGENTS.md, CLAUDE.md, CODEX.md, GEMINI.md, .github/copilot-instructions.md, .github/instructions/*.instructions.md, Cursor rules, and related files. It flags instructions that bypass approvals, treat untrusted GitHub text as commands, or expose secrets. Includes examples, remediation guidance, graph/migration support, docs, and tests.