feat(home): add pass-backed keyring module and enable for work VM

- Add modules/home/security/pass-keyring with GPG agent, pass, and
  python keyring backend config for headless credential storage
- Enable pass-keyring for lin-va-mbp-work-vm
- Update bash PATH from ~/.bin to ~/.local/bin

homes/aarch64-linux/evanreichard@lin-va-mbp-work-vm/default.nix

@@ -20,6 +20,7 @@ in
     };
 
     security = {
+      pass-keyring = enabled;
       sops = enabled;
     };