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/templates/jobs.html

@@ -0,0 +1,16 @@
+{{ define "page_jobs" }}
+<section class="card">
+  <div class="section-head">
+    <h1>Your Jobs</h1>
+    <a href="/jobs/new" class="btn primary">New Job</a>
+  </div>
+  <div
+    id="jobs-fragment"
+    hx-get="/ui/fragments/jobs"
+    hx-trigger="load, every 5s"
+    hx-swap="innerHTML"
+  >
+    <p>Loading jobs...</p>
+  </div>
+</section>
+{{ end }}