fix(docs): add base to og image using env variable

docs/.gitlab-ci.yml

@@ -40,7 +40,7 @@ build-production:
     name: production
     url: https://docs.castopod.org/
   script:
-    - pnpm run build --outDir=./dist/$CI_COMMIT_REF_SLUG --base=$CI_COMMIT_REF_SLUG
+    - BASE=/$CI_COMMIT_REF_SLUG pnpm run build --outDir=./dist/$CI_COMMIT_REF_SLUG --base=/$CI_COMMIT_REF_SLUG
   artifacts:
     paths:
       - docs/dist/$CI_COMMIT_REF_SLUG

docs/astro.config.mjs

@@ -4,11 +4,12 @@ import starlight from "@astrojs/starlight";
 import tailwind from "@astrojs/tailwind";
 
 const site = "https://docs.castopod.org/";
+const base = process.env.BASE ?? "/docs";
 
 // https://astro.build/config
 export default defineConfig({
   site,
-  base: "/docs",
+  base,
   integrations: [
     starlight({
       title: "Castopod Docs",
@@ -37,7 +38,7 @@ export default defineConfig({
           tag: "meta",
           attrs: {
             property: "og:image",
-            content: site + "open-graph.jpg?v=1",
+            content: base + "/open-graph.jpg?v=1",
           },
         },
         {