Refactor Zasilkovna client, update imports and cleanup

Refactored the Zasilkovna SOAP client to use a singleton pattern with caching and lazy loading, improving reliability and startup performance. Updated invoice PDF generation to import WeasyPrint lazily, preventing startup failures on systems missing dependencies. Cleaned up unused imports and code in several frontend components, removed unused state and variables, and adjusted Docker frontend port mapping. Also updated Django migration files to reflect a new generation timestamp.

backend/thirdparty/downloader/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 5.2.9 on 2025-12-14 02:23
+# Generated by Django 5.2.7 on 2025-12-18 15:11
 
 from django.db import migrations, models
 

backend/thirdparty/gopay/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 5.2.9 on 2025-12-14 02:23
+# Generated by Django 5.2.7 on 2025-12-18 15:11
 
 import django.db.models.deletion
 import django.utils.timezone

backend/thirdparty/stripe/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 5.2.9 on 2025-12-14 02:23
+# Generated by Django 5.2.7 on 2025-12-18 15:11
 
 from django.db import migrations, models
 

backend/thirdparty/zasilkovna/client.py

@@ -1,28 +1,49 @@
 from zeep import Client
 from zeep.exceptions import Fault
+from zeep.transports import Transport
+from zeep.cache import SqliteCache
 
+import tempfile
 import base64
 import logging
 import os
 
+from functools import lru_cache
+
 logger = logging.getLogger(__name__)
 
 WSDL_URL = os.getenv("PACKETA_WSDL_URL", "https://www.zasilkovna.cz/api/soap.wsdl")
 PACKETA_API_PASSWORD = os.getenv("PACKETA_API_PASSWORD")
 
 
-zeepZasClient = Client(wsdl=WSDL_URL)
+
+
+# --- 1. Singleton pro klienta (aby se WSDL stáhlo jen jednou pro celý proces) ---
+@lru_cache(maxsize=1)
+def get_shared_client():
+    """
+    Tato funkce vrátí instanci klienta a drží ji v tempfile na jednu hodinu.
+    """
+    if not PACKETA_API_PASSWORD:
+        raise ValueError("Packeta API password is not set.")
+    
+    
+    tempFpath = os.path.join(tempfile.gettempdir(), 'zeep_packeta_cache.db')
+    transport = Transport(cache=SqliteCache(path=tempFpath, timeout=3600))
+    
+    return Client(wsdl=WSDL_URL, transport=transport)
 
 
 class PacketaAPI:
-    #TODO: zeptat se jestli nepřidat další checkovací parametry ohledně zásilkovny např: blokování podle configurace webu
-    # popřemýšlet, jestli api klíče nenastavit přes configurator webu
-    def __getattribute__(self):
-        if PACKETA_API_PASSWORD in [None, ""]:
-            raise Exception("Packeta API password is not set in environment variables.")
+    # --- 2. Property pro lazy loading ---
+    @property
+    def client(self):
+        """
+        Při zavolání self.client se zavolá tento kód.
+        Vrátí již existujícího klienta z cache.
+        """
+        return get_shared_client()
         
-        elif zeepZasClient is None:
-            raise Exception("Packeta SOAP client is not initialized.")
     
     # ---------- CREATE PACKET METHODS ----------
 
@@ -68,7 +89,7 @@ class PacketaAPI:
 
         try:
             # Použijeme createPacketClaimWithPassword, protože umožňuje ukládat email a telefon
-            result = zeepZasClient.service.createPacketClaimWithPassword(PACKETA_API_PASSWORD, attributes)
+            result = self.client.service.createPacketClaimWithPassword(PACKETA_API_PASSWORD, attributes)
             return result
 
         except Fault as e:
@@ -83,7 +104,7 @@ class PacketaAPI:
         packet_id = 1234567890
         """
         try:
-            zeepZasClient.service.cancelPacket(PACKETA_API_PASSWORD, packet_id)
+            self.client.service.cancelPacket(PACKETA_API_PASSWORD, packet_id)
 
             return {"status": "ok", "message": f"Zásilka {packet_id} byla zrušena."}
         
@@ -99,7 +120,7 @@ class PacketaAPI:
         Vrací datum do kdy je uložená zásilka.
         """
         try:
-            request = zeepZasClient.service.packetGetStoredUntil(PACKETA_API_PASSWORD, packet_id)
+            request = self.client.service.packetGetStoredUntil(PACKETA_API_PASSWORD, packet_id)
             if request is None:
                 raise Exception(f"Zásilka {packet_id} nebyla ještě doručena.")
             
@@ -128,7 +149,7 @@ class PacketaAPI:
             bytes: PDF soubor (base64 dekódovaný)
         """
         try:
-            pdf_base64 = zeepZasClient.service.packetLabelPdf(
+            pdf_base64 = self.client.service.packetLabelPdf(
                 PACKETA_API_PASSWORD, packet_id, format, offset
             )
 
@@ -163,7 +184,7 @@ class PacketaAPI:
         packet_ids = ["1234567890", "1234567891", "1234567892"]
         """
         try:
-            result = zeepZasClient.service.createShipment(PACKETA_API_PASSWORD, packet_ids)
+            result = self.client.service.createShipment(PACKETA_API_PASSWORD, packet_ids)
 
             return result
         
@@ -176,7 +197,7 @@ class PacketaAPI:
         Získá seznam balíků ve shipmentu podle jeho shipmentId.
         """
         try:
-            result = zeepZasClient.service.shipmentPackets(PACKETA_API_PASSWORD, shipment_id)
+            result = self.client.service.shipmentPackets(PACKETA_API_PASSWORD, shipment_id)
             return result
         except Fault as e:
             logger.error(f"Packeta shipmentPackets error: {e}")

backend/thirdparty/zasilkovna/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 5.2.9 on 2025-12-14 02:23
+# Generated by Django 5.2.7 on 2025-12-18 15:11
 
 import django.core.validators
 from django.db import migrations, models