chore(pr): pin force-UI evidence to PR #1146 and HEAD SHA

Rename .github/pr-assets/PLACEHOLDER_PR -> .github/pr-assets/1146 and
substitute {HEAD_SHA_PLACEHOLDER} with the current HEAD so commit-pinned
raw GitHub URLs in the HTML report resolve correctly.

The pinned SHA in this commit is the parent commit; once this commit is
pushed, the PR body references will resolve via the htmlpreview.github.io
proxy against the parent SHA. Reviewers see frozen-in-time evidence.

Refs #1142, #1138

.github/pr-assets/1146/logs-redesign.html

@@ -208,8 +208,8 @@
             <li>User / dataset / fixture / theme / viewport held constant within each capture.</li>
             <li>Callouts: DOM overlay injected via Playwright <code>browser_evaluate</code>, red <code>#ef4444</code> 3px solid border, 8px expanded padding (no ImageMagick).</li>
             <li>Capture tool: Playwright MCP. Annotations baked into the PNG by injecting overlay divs before screenshot.</li>
-            <li>HEAD SHA: <code>{HEAD_SHA_PLACEHOLDER}</code> - orchestrator pins after final commit.</li>
-            <li>PR number: <code>PLACEHOLDER_PR</code> - orchestrator renames asset directory after PR creation.</li>
+            <li>HEAD SHA: <code>1c814787a671be1121154b1c72f48932ec4f9904</code> - orchestrator pins after final commit.</li>
+            <li>PR number: <code>1146</code> - orchestrator renames asset directory after PR creation.</li>
           </ul>
         </div>
       </section>