wire postgres session repo, migrations, seed, and dev serve

process-compose.yml

@@ -1,9 +1,22 @@
-version: "1"
+version: "0.5"
 
 processes:
+  postgres:
+    command: postgres -D "$PGDATA" -k "$PGDATA" -c listen_addresses=127.0.0.1
+    shutdown:
+      signal: 2
+    readiness_probe:
+      exec:
+        command: pg_isready -h "$PGDATA"
+      initial_delay_seconds: 1
+      period_seconds: 2
+
   backend:
-    command: php -S 127.0.0.1:8000 -t backend/public/
+    command: bash backend/bin/serve
     working_dir: .
+    depends_on:
+      postgres:
+        condition: process_healthy
     availability:
       restart: always