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/job_new.html

@@ -0,0 +1,60 @@
+{{ define "page_jobs_new" }}
+<section id="job-upload-section" class="card">
+  <h1>Create Render Job</h1>
+  <div class="stepper">
+    <div id="step-upload" class="step active">1. Upload & Analyze</div>
+    <div id="step-config" class="step">2. Review & Submit</div>
+  </div>
+
+  <form id="upload-analyze-form" class="stack">
+    <label>Upload Blend/ZIP
+      <input type="file" id="source-file" name="file" accept=".blend,.zip,application/zip,application/x-zip-compressed" required>
+    </label>
+    <label id="main-blend-wrapper" class="hidden">Main Blend (for ZIP with multiple .blend files)
+      <select id="main-blend-select"></select>
+    </label>
+    <button type="submit" class="btn primary">Upload and Analyze</button>
+  </form>
+
+  <div id="upload-status" class="stack hidden"></div>
+  <p id="job-create-error" class="alert error hidden"></p>
+</section>
+
+<section id="job-config-section" class="card hidden">
+  <h2>Review Render Settings</h2>
+  <p class="muted">Values are prefilled from extracted metadata; adjust before submission.</p>
+  <div id="metadata-preview" class="stack"></div>
+
+  <form id="job-config-form" class="stack">
+    <label>Job Name
+      <input type="text" id="job-name" name="name" required>
+    </label>
+    <div class="grid-2">
+      <label>Frame Start
+        <input type="number" id="frame-start" name="frame_start" min="0" required>
+      </label>
+      <label>Frame End
+        <input type="number" id="frame-end" name="frame_end" min="0" required>
+      </label>
+    </div>
+    <label>Output Format
+      <select name="output_format" id="output-format">
+        <option value="EXR">EXR</option>
+        <option value="EXR_264_MP4">EXR + H264 MP4</option>
+        <option value="EXR_AV1_MP4">EXR + AV1 MP4</option>
+        <option value="EXR_VP9_WEBM">EXR + VP9 WEBM</option>
+      </select>
+    </label>
+    <label>Blender Version (optional)
+      <select name="blender_version" id="blender-version">
+        <option value="">Auto-detect from file</option>
+      </select>
+    </label>
+    <div class="check-row">
+      <label><input type="checkbox" id="unhide-objects" name="unhide_objects"> Unhide objects/collections</label>
+      <label><input type="checkbox" id="enable-execution" name="enable_execution"> Enable auto-execution in Blender</label>
+    </div>
+    <button type="submit" class="btn primary">Create Job</button>
+  </form>
+</section>
+{{ end }}