feat: persist CLI credentials for client creation

[Magic-Jia]

Summary

• Persist API token, TLS certificate path, and TLS certificate key path in the CLI profile config
• Create Permify clients from the full persisted config instead of only the endpoint
• Add bearer token per-RPC credentials and TLS client certificate support for gRPC connections
• Write config files with owner-only permissions because they may now contain credentials

Test Plan

• go test ./...
• make build
• git diff --check

Closes #2
/claim #2