docs: add community call schedule and join link

Replace TBD placeholders on the Community calls page with the bi-weekly
Tuesday schedule, the LFX public calendar, and the Zoom meeting link.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

On-behalf-of: @SAP mirza.kopic@sap.com
Signed-off-by: Mirza Kopić <mirza.kopic@gmail.com>

Author: mirzakopic

community/calls.md

@@ -2,20 +2,16 @@
 
 Platform Mesh community calls are open meetings for project discussions, demos, and Q&A.
 
-::: info
-The first community call has not yet taken place. This page is updated with the schedule and joining instructions once announced.
-:::
-
 ## Schedule
 
-TBD.
+The community call runs every two weeks on Tuesday at 16:00 CET (15:00 UTC during standard time, 14:00 UTC during daylight saving).
 
-## How to join
+Subscribe to the [Platform Mesh public calendar](https://zoom-lfx.platform.linuxfoundation.org/meetings/platform-mesh) to see upcoming meetings in your local time.
 
-TBD.
+## How to join
 
-## Agenda and notes
+[Join the community call on Zoom](https://zoom-lfx.platform.linuxfoundation.org/meeting/93538459120?password=6fe4d0da-3a68-4b4d-9f65-7330007ed8cc).
 
-TBD.
+Meeting ID: `93538459120`.
 
 Recorded talks and presentations are listed under [Talks](./talks.md).