Refactor web build process and update documentation

- Removed Node.js build artifacts from .gitignore and adjusted Makefile to reflect changes in web UI build process, now using server-rendered Go templates instead of React.
- Updated README to clarify the new web UI architecture and output formats, emphasizing the removal of the Node.js build step.
- Added a command to set the number of frames per render task in manager configuration, enhancing user control over rendering settings.
- Improved Gitea workflow by removing unnecessary npm install step, streamlining the CI process.

web/static/jobs.js

@@ -0,0 +1,41 @@
+(function () {
+  async function apiRequest(url, method) {
+    const res = await fetch(url, {
+      method,
+      credentials: "include",
+      headers: { "Content-Type": "application/json" },
+    });
+    const data = await res.json().catch(() => ({}));
+    if (!res.ok) {
+      throw new Error(data.error || "Request failed");
+    }
+    return data;
+  }
+
+  document.body.addEventListener("click", async (e) => {
+    const cancelBtn = e.target.closest("[data-cancel-job]");
+    const deleteBtn = e.target.closest("[data-delete-job]");
+    if (!cancelBtn && !deleteBtn) return;
+
+    try {
+      if (cancelBtn) {
+        const id = cancelBtn.getAttribute("data-cancel-job");
+        if (!confirm("Cancel this job?")) return;
+        await apiRequest(`/api/jobs/${id}`, "DELETE");
+      }
+      if (deleteBtn) {
+        const id = deleteBtn.getAttribute("data-delete-job");
+        if (!confirm("Delete this job permanently?")) return;
+        await apiRequest(`/api/jobs/${id}/delete`, "POST");
+      }
+      if (window.htmx) {
+        htmx.trigger("#jobs-fragment", "refresh");
+        htmx.ajax("GET", "/ui/fragments/jobs", "#jobs-fragment");
+      } else {
+        window.location.reload();
+      }
+    } catch (err) {
+      alert(err.message);
+    }
+  });
+})();