chore(tests): organize test scripts and beautify account creation email

- Moved scattered Python test scripts from root and 'admin/development/' to 'tests/'.
- Beautified the HTML email body for account creation links in 'app/methods/person_methods.py' with a modern responsive design.

tests/diagnose_boot.py

@@ -0,0 +1,54 @@
+import sys
+import os
+
+print("--- Starting Import Diagnosis ---")
+
+try:
+    print("1. Importing app.config...")
+    from app import config
+    print(f"   Success. Settings found: {hasattr(config, 'settings')}")
+except Exception as e:
+    print(f"   FAILED: {e}")
+    sys.exit(1)
+
+try:
+    print("2. Importing app.log...")
+    import app.log
+    print("   Success.")
+except Exception as e:
+    print(f"   FAILED: {e}")
+    import traceback
+    traceback.print_exc()
+    sys.exit(1)
+
+try:
+    print("3. Importing app.db_connection...")
+    import app.db_connection
+    print("   Success.")
+except Exception as e:
+    print(f"   FAILED: {e}")
+    import traceback
+    traceback.print_exc()
+    sys.exit(1)
+
+try:
+    print("4. Importing app.db_sql...")
+    import app.db_sql
+    print("   Success.")
+except Exception as e:
+    print(f"   FAILED: {e}")
+    import traceback
+    traceback.print_exc()
+    sys.exit(1)
+
+try:
+    print("5. Importing app.main...")
+    import app.main
+    print("   Success.")
+except Exception as e:
+    print(f"   FAILED: {e}")
+    import traceback
+    traceback.print_exc()
+    sys.exit(1)
+
+print("--- Diagnosis Complete: No top-level import errors found in local env ---")