web-app-chess: refactor runtime & entrypoint

- Move entrypoint to files/ and deploy via copy
- Parameterize APP_KEY_FILE, data dir, and entrypoint paths
- Require explicit PORT/PG envs (remove fallbacks)
- Drop stray header from config/main.yml
- Dockerfile: use templated data dir & entrypoint; keep node user
- Compose: set custom image, adjust volume mapping
- env: derive APP_SCHEME from WEB_PROTOCOL; NODE_ENV from ENVIRONMENT
- tasks: add 01_core and simplify main to include it

Ref: https://chatgpt.com/share/68b851c5-4dd8-800f-8e9e-22b985597b8f

roles/web-app-chess/tasks/01_core.yml

@@ -0,0 +1,10 @@
+- name: "load docker, db and proxy for {{ application_id }}"
+  include_role:
+    name: sys-stk-full-stateful
+
+- name: "Deploy '{{ CHESS_ENTRYPOINT_ABS }}'"
+  copy:
+    src:    "{{ CHESS_ENTRYPOINT_FILE }}"
+    dest:   "{{ CHESS_ENTRYPOINT_ABS }}"
+
+- include_tasks: utils/run_once.yml