Add build verification and test credential checking

- Build script now shows summary of embedded credentials after build
- quick-test.sh now checks if binary has credentials before running
- This prevents the "dial tcp :143" empty server error

Tests if help output shows empty string in default values.

quick-test.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 # Quick Test Script for nextcloud-mail
-# Usage: ./quick-test.sh <username>
+# Usage: ./quick-test.sh
 
 set -e
 
@@ -11,6 +11,20 @@ echo "========================================="
 echo "nextcloud-mail Quick Test Suite"
 echo "========================================="
 echo ""
+
+# Check if binary has credentials before running
+echo "Checking binary credentials..."
+if ~/bin/nextcloud-mail --help 2>&1 | grep -q '"imap-server".*"\"\"'; then
+  echo "❌ Error: nextcloud-mail binary was built with empty credentials!"
+  echo "   Please run ./build.sh again and provide valid IMAP/SMTP credentials."
+  echo ""
+  echo "Current binary shows:"
+  ~/bin/nextcloud-mail --help 2>&1 | grep -A2 '"imap-server"'
+  echo ""
+  exit 1
+fi
+
+echo "✓ Binary has credentials configured"
 echo "Username: $USERNAME"
 echo "Test Directory: $TEST_DIR"
 echo ""