fix: Lighthouse CI tests canonical upstream URL

The Lighthouse CI job in test.yml has been failing on every merge to
main since at least 2026-04-06 (10 consecutive failures) because
.lighthouserc.json tests https://raifdmueller.github.io/Semantic-Anchors/
— the fork URL, which is a leftover from when development happened in
the fork before the move to upstream.

The fork GH Pages site hasn't been redeployed since 2026-03-27
(confirmed via HTTP last-modified headers), so Lighthouse is testing an
outdated snapshot that doesn't reflect anything recent.

Point the test at https://llm-coding.github.io/Semantic-Anchors/ —
the canonical deployed URL that deploy.yml actually publishes to.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: raifdmueller

website/.lighthouserc.json

@@ -1,7 +1,7 @@
 {
   "ci": {
     "collect": {
-      "url": ["https://raifdmueller.github.io/Semantic-Anchors/"],
+      "url": ["https://llm-coding.github.io/Semantic-Anchors/"],
       "numberOfRuns": 3,
       "settings": {
         "preset": "desktop"