feat: add logging and SMTP error handling

Logging:
- Add structured logging with timestamps
- Log successful and failed login attempts
- Log new orders and order completions
- Log email sending success/failures

SMTP Error Handling:
- Add try/except block around SMTP operations
- Catch authentication errors, SMTP exceptions, and general errors
- Log all email failures with detailed error messages
- Ensure orders are saved even if email fails

This allows monitoring of critical operations and troubleshooting
email delivery issues through systemd journal.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

wawi/app.py

@@ -14,6 +14,7 @@ import secrets
 import smtplib
 import time
 import threading
+import logging
 from uuid import uuid4
 from email.message import EmailMessage
 from functools import wraps
@@ -31,6 +32,14 @@ DB_PATH = BASE_DIR / "hellas.db"
 UPLOAD_DIR = BASE_DIR / "static" / "uploads"
 ALLOWED_EXT = {".png", ".jpg", ".jpeg", ".webp", ".gif"}
 
+# Logging konfigurieren
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s [%(levelname)s] %(name)s: %(message)s',
+    datefmt='%Y-%m-%d %H:%M:%S'
+)
+logger = logging.getLogger(__name__)
+
 # Optionaler Prefix (z. B. /wawi), wenn die App hinter einem Sub‑Pfad läuft.
 URL_PREFIX = os.environ.get("URL_PREFIX", "").strip().rstrip("/")
 STATIC_URL_PATH = f"{URL_PREFIX}/static" if URL_PREFIX else "/static"
@@ -490,8 +499,10 @@ def login():
         ).fetchone()
         if row and check_password_hash(row["password_hash"], password):
             session["user"] = user
+            logger.info(f"Erfolgreicher Login: {user}")
             nxt = request.args.get("next") or url_for("bp.index")
             return redirect(nxt)
+        logger.warning(f"Fehlgeschlagener Login-Versuch: {user}")
         return render_template("login.html", error=True)
     return render_template("login.html", error=False)
 
@@ -653,6 +664,7 @@ def order():
         ),
     )
     db.commit()
+    logger.info(f"Neue Bestellung: {data.get('artikel')} ({data.get('groesse')}) x{data.get('menge')} von {data.get('name')}")
 
     to_addr = os.environ.get("ORDER_TO", "bjoern@welker.me")
     smtp_host = os.environ.get("SMTP_HOST")
@@ -683,10 +695,19 @@ def order():
     msg.set_content(body)
 
     def _send():
+        """Sendet Bestellungs-Email asynchron mit Error Handling."""
+        try:
             with smtplib.SMTP(smtp_host, smtp_port) as server:
                 server.starttls()
                 server.login(smtp_user, smtp_pass)
                 server.send_message(msg, to_addrs=recipients)
+            logger.info(f"Bestellungs-Email erfolgreich versendet an {', '.join(recipients)}")
+        except smtplib.SMTPAuthenticationError as e:
+            logger.error(f"SMTP-Authentifizierung fehlgeschlagen: {e}")
+        except smtplib.SMTPException as e:
+            logger.error(f"SMTP-Fehler beim Email-Versand: {e}")
+        except Exception as e:
+            logger.error(f"Unerwarteter Fehler beim Email-Versand: {e}", exc_info=True)
 
     threading.Thread(target=_send, daemon=True).start()
 
@@ -758,6 +779,7 @@ def complete_order(order_id: int):
             (user, now_iso(), order_id),
         )
         db.commit()
+        logger.info(f"Bestellung #{order_id} abgeschlossen von {user}")
     return redirect(url_for("bp.orders"))