💚 Reuse npm cache in publish job

The publish job ran npm ci against a cold cache on every release while
build/maintain already share a warm node-cache key off the same lockfile.
Tag runs can read caches saved on main, so wiring cache: npm here is free.

.gitea/workflows/ci.yml

@@ -139,6 +139,10 @@ jobs:
             - uses: actions/setup-node@v4
               with:
                   node-version-file: .node-version
+                  # Same lockfile/key as `build`, and tag runs can read caches
+                  # saved on `main` — without this, every release pays a cold
+                  # `npm ci` despite the warm shared npm cache.
+                  cache: "npm"
                   registry-url: "https://registry.npmjs.org/"
             - run: npm ci
             # Consume the dist/ that `build` produced and gated, instead of