FE: adopt build-time API base (config.js) + build FE image in CI

Merge the deployment mechanism from main into this (sky-map) branch so the
map version is deployable the same way:

A) Build-time API base via config.js
   - frontend/config.js: window.API_BASE (default /api)
   - app.js reads window.API_BASE instead of hardcoding the API host
   - index.html loads config.js before app.js
   - docker/fe/Dockerfile bakes config.js from the API_BASE build arg
   - docker-compose.yml dev build passes API_BASE=http://localhost:8000

B) CI builds and pushes ghcr.io/bolidozor/meteorpointer-fe (with the sky map)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: robozor

.github/workflows/release.yml

@@ -41,3 +41,24 @@ jobs:
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+
+      - name: Docker metadata for FE (tags + labels)
+        id: meta-fe
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/bolidozor/meteorpointer-fe
+          tags: |
+            type=raw,value=latest,enable={{is_default_branch}}
+            type=ref,event=branch
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha
+
+      - name: Build and push FE image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: docker/fe/Dockerfile
+          push: true
+          tags: ${{ steps.meta-fe.outputs.tags }}
+          labels: ${{ steps.meta-fe.outputs.labels }}

docker-compose.yml

@@ -56,6 +56,10 @@ services:
     build:
       context: .
       dockerfile: docker/fe/Dockerfile
+      args:
+        # Dev: FE on :8080 talks to the API on :8000 directly (no /api prefix,
+        # no proxy). Production builds keep the default `/api`.
+        API_BASE: http://localhost:8000
     container_name: MeteorPointer-FE
     depends_on:
       - api

docker/fe/Dockerfile

@@ -1,5 +1,13 @@
 # Minimal login-test frontend container (static files via nginx).
 # The real frontend (MeteorPointer-FE / webUI) will replace this.
 FROM nginx:1.27-alpine
+
+# API base baked into config.js. Defaults to `/api` (production: same origin,
+# proxy serves the API under :443/api/ and strips the prefix). Override per
+# environment, e.g. --build-arg API_BASE=http://localhost:8000 for local dev.
+# Must NOT end with a slash.
+ARG API_BASE=/api
+
 COPY frontend/ /usr/share/nginx/html/
+RUN printf "window.API_BASE = '%s';\n" "$API_BASE" > /usr/share/nginx/html/config.js
 EXPOSE 80

frontend/app.js

@@ -1,6 +1,9 @@
 // Minimal login-test frontend. The real frontend (framework, full UI) follows.
-// The API is assumed to run on the same host, port 8000.
-const API = `${location.protocol}//${location.hostname}:8000`;
+// API base is injected at build time via config.js (window.API_BASE). It must
+// NOT end with a slash. Default `/api` matches the production deployment, where
+// the proxy serves the API under :443/api/ and strips the /api prefix before
+// forwarding to the container. Dev (FE on :8080) overrides it to the API host.
+const API = (window.API_BASE ?? '/api');
 const t = (k, v) => window.MPI18n.t(k, v);
 
 const $ = (id) => document.getElementById(id);

frontend/config.js

@@ -0,0 +1,4 @@
+// Runtime config. The Docker image overwrites this at build time from the
+// API_BASE build arg (docker/fe/Dockerfile). Must NOT end with a slash.
+// `/api` = same origin, production proxy under :443/api/.
+window.API_BASE = '/api';

frontend/index.html

@@ -162,6 +162,7 @@ <h3 data-i18n="about_box.coordsH"></h3>
       </div>
     </div>
 
+    <script src="config.js"></script>
     <script src="i18n.js"></script>
     <script src="sky.js"></script>
     <script src="app.js"></script>