Add self-hosted PocketBase stack with auto-migrations

- docker-compose.yml: app + pocketbase services (PB internal to the network)
- pocketbase/: pinned PocketBase image, superuser bootstrap via env vars
- pb_migrations: production schema (collections, rules, public_users view)
  applied automatically on first boot
- pocketbase/pb_schema.json: schema export kept as reference
- README: full-stack deployment docs

docker-compose.yml

@@ -0,0 +1,28 @@
+# Full PokeShare stack: the Astro app and its PocketBase backend.
+# In Coolify, deploy this file as a "Docker Compose" resource.
+# The `app` service is the one to expose on your public domain.
+# `pocketbase` stays on the internal network — expose it on a subdomain
+# only if you want to reach the admin UI (/_/) from outside.
+services:
+    pocketbase:
+        build: ./pocketbase
+        restart: unless-stopped
+        environment:
+            # Optional: create/update the admin account on boot (min 8 chars)
+            PB_SUPERUSER_EMAIL: ${PB_SUPERUSER_EMAIL:-}
+            PB_SUPERUSER_PASSWORD: ${PB_SUPERUSER_PASSWORD:-}
+        volumes:
+            - pb_data:/pb/pb_data
+
+    app:
+        build: .
+        restart: unless-stopped
+        environment:
+            # Internal service URL — the browser never talks to PocketBase
+            # directly, everything goes through the Astro server.
+            POCKETBASE_URL: http://pocketbase:8090
+        depends_on:
+            - pocketbase
+
+volumes:
+    pb_data: