feat: Add Matrix infrastructure (Synapse + Element Web)

- Synapse homeserver.yaml configuration
- Element Web config.json
- PostgreSQL init script for synapse DB
- Nginx gateway configuration
- Docker Compose for Matrix stack
- README_MATRIX.md documentation

infra/matrix/synapse/log.config

@@ -0,0 +1,21 @@
+version: 1
+
+formatters:
+  precise:
+    format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'
+
+handlers:
+  console:
+    class: logging.StreamHandler
+    formatter: precise
+
+loggers:
+  synapse.storage.SQL:
+    level: WARNING
+
+root:
+  level: INFO
+  handlers: [console]
+
+disable_existing_loggers: false
+