feat: MAS as auth provider + remove synapse-admin

- Migrate Synapse SQLite -> Postgres (synapse_port_db)
- Enable MSC3861 (matrix_authentication_service block)
- Disable password_config legacy
- Add bcrypt passwords scheme to MAS
- Register 4 MAS clients (element, matrix_pc, matrix_android, admin_panel)
- syn2mas migrated 21 users + 41 access_tokens
- Patch well-known with org.matrix.msc2965.authentication
- Remove synapse-admin container (replaced by custom admin panel — issue 0163)

Issue: 0162
Refs: dev/flows/0010-matrix-client-pc.md, dev/flows/0011-matrix-client-android.md

docker-compose.yml

@@ -53,16 +53,17 @@ services:
       - UID=1000
       - GID=1000
 
-  synapse-admin:
+  # synapse-admin removed 2026-05-24 — replaced by custom admin panel (issue 0163)
-    image: awesometechnologies/synapse-admin:latest
+  # synapse-admin:
-    restart: unless-stopped
+  # image: awesometechnologies/synapse-admin:latest
-    networks:
+  # restart: unless-stopped
-      default:
+  # networks:
-        ipv4_address: 10.10.10.5
+  # default:
-    ports:
+  # ipv4_address: 10.10.10.5
-      - "8082:80"
+  # ports:
-    depends_on:
+  # - "8082:80"
-      - synapse
+  # depends_on:
+  # - synapse
 
   mas:
     image: ghcr.io/element-hq/matrix-authentication-service:latest