Step 6c: extract Diagnostics + Profiles + Rules Editors from options.js

Final options.js split. Three new files:

  options-diagnostics.js     245 lines
  options-profiles.js        265 lines
  options-rules-editors.js   328 lines  (adapters + ID normalizers
                                          + custom part detectors)

options.js: 1852 → 1014 lines (838 extracted, ~45% reduction).

Script-tag order in options.html now (load order matters for
top-level let bindings shared across files, e.g. _configuredScanRoots):

  options-cache.js
  options-dupe-review.js
  options-library-issues.js
  options-diagnostics.js
  options-profiles.js
  options-rules-editors.js
  options.js  (entry: IIFE bottom, escapeHtml, overlay previews,
               element picker, paths)

The picker, overlay-preview, and no-match overlay code stays in
options.js — those are tightly intertwined with multiple settings
panes and not worth further splitting today.

node --check passes on each file individually and on the concatenated
load-order stream. Line count of concat (3144) matches the pre-split
sum exactly.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

options.html

@@ -794,6 +794,9 @@
 <script src="options-cache.js"></script>
 <script src="options-dupe-review.js"></script>
 <script src="options-library-issues.js"></script>
+<script src="options-diagnostics.js"></script>
+<script src="options-profiles.js"></script>
+<script src="options-rules-editors.js"></script>
 <script src="options.js"></script>
 </body>
 </html>