Add GPG agent configuration for weekly key renewal

- Ask for passphrase every week (7 days)
- Maximum cache time of 1 month (30 days)
- Applies to both GPG and SSH keys
- Enables passphrase confirmation for security

.gpg/gpg-agent.conf

@@ -0,0 +1,10 @@
+# GPG Agent Configuration - Weekly renewal with monthly maximum
+# Ask for passphrase every week (604800 seconds = 7 days)
+default-cache-ttl 604800
+# Maximum cache time is 1 month (2592000 seconds = 30 days)
+max-cache-ttl 2592000
+# Same settings for SSH keys
+default-cache-ttl-ssh 604800
+max-cache-ttl-ssh 2592000
+# Enable passphrase confirmation
+allow-preset-passphrase