fix(home): cache GPG agent passphrase for 24 hours (#335)

Set defaultCacheTtl and maxCacheTtl to 86400 seconds so the GPG
passphrase only needs to be entered once per day, preventing repeated
prompts during automated git operations.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: stackptr

home/services.nix

@@ -2,6 +2,8 @@
   services.gpg-agent = {
     enable = true;
     enableZshIntegration = true;
+    defaultCacheTtl = 86400;
+    maxCacheTtl = 86400;
     pinentry.package = with pkgs;
       if stdenv.isDarwin
       then pinentry_mac