Add VTIMEZONE definition for Google Calendar timezone recognition

Google Calendar showed UTC instead of Europe/Warsaw because the iCal
feed lacked a VTIMEZONE component. Added full CET/CEST definition.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

blueprints/community/calendar/routes.py

@@ -388,6 +388,24 @@ def ical_feed():
             'X-WR-TIMEZONE:Europe/Warsaw',
             'REFRESH-INTERVAL;VALUE=DURATION:PT6H',
             'X-PUBLISHED-TTL:PT6H',
+            # VTIMEZONE for Google Calendar to recognize Europe/Warsaw
+            'BEGIN:VTIMEZONE',
+            'TZID:Europe/Warsaw',
+            'BEGIN:STANDARD',
+            'DTSTART:19701025T030000',
+            'RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10',
+            'TZOFFSETFROM:+0200',
+            'TZOFFSETTO:+0100',
+            'TZNAME:CET',
+            'END:STANDARD',
+            'BEGIN:DAYLIGHT',
+            'DTSTART:19700329T020000',
+            'RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3',
+            'TZOFFSETFROM:+0100',
+            'TZOFFSETTO:+0200',
+            'TZNAME:CEST',
+            'END:DAYLIGHT',
+            'END:VTIMEZONE',
         ]
 
         for event in events: