🛡️ Sentinel: Secure socket creation in private directory

[minibota]

🔐 Issue: The daemon created its Unix socket directly in /tmp/ with a predictable name (cc-agent-<user>.sock). This allowed local attackers to pre-create the socket file (DoS) or potentially hijack the connection if directory permissions were loose.

🧠 Risk: Denial of Service (preventing agent startup) or Information Disclosure (if attacker tricks exec command into connecting to their socket).

🛠️ Fix:

• Changed socket location to a private subdirectory: /tmp/cc-agent-<uid>/cc-agent.sock (or /tmp/cc-agent-<user>/ on Windows).
• Added ensureSocketDir helper to enforce 0700 permissions on this directory before creation.
• Updated daemon to use this new secure path logic.

🧪 Tests:

• Added TestEnsureSocketDir to verify directory creation and permission enforcement.
• Ran existing tests go test -v ./cmd/... (passed).

📎 Notes:

• This is a BREAKING CHANGE for the socket path. However, the agent automatically updates the managed cron file with the new path upon startup (via sync_jobs), so service disruption should be minimal (only pending jobs during the restart window might fail).
• exec command automatically picks up the new path if --socket-path is not specified, or via the updated cron job arguments.

Automated nightly security task.

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PR created automatically by Jules for task 10612344924168496973 started by @minibota

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