docs(agent): enforce mandatory signed commit policy in AGENTS.md

Author: iseki0

AGENTS.md

@@ -0,0 +1,9 @@
+# Agent Rules
+
+## Git Commit Signing (MANDATORY)
+
+1. This repository enforces signed commits as a mandatory rule. Every `git commit` must be signed (GPG or SSH signing, following local Git configuration).
+2. `--no-gpg-sign`, disabling signing config, or any equivalent bypass is strictly prohibited.
+3. In this Windows sandbox environment, commit signing will predictably fail without elevation (for example, keyring/lockfile/pinentry access issues). Do not make repeated non-elevated commit attempts.
+4. If signing fails or is expected to fail in sandbox, you must immediately request escalation and retry with signing enabled.
+5. If escalation is not granted, stop and ask the user how to proceed. Do not create an unsigned commit.