refactor: rework API loader and caching

This commit removes dependency on rxjs.

It also implements better composables to handle data fetching from
remote APIs and caching these values more transparently.

This commit also switches from yarn to npm

It also switches to the official Umami plugin

.gitea/workflows/deploy.yaml

@@ -11,15 +11,14 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v4
         with:
-          node-version: 18.x
-      - run: corepack enable
-      - run: yarn install --frozen-lockfile
+          node-version: 22.x
+      - run: npm ci
       - uses: purcell/setup-emacs@master
         with:
           version: 29.1
       - name: "Export org to md"
         run: emacs -Q --script export.el
-      - run: yarn build
+      - run: npm run build
       - name: "Deploy on the Web"
         uses: appleboy/scp-action@v0.1.7
         with: