test(e2e): thread-panel aria snapshot includes "started by …" (#165)

The thread header subtitle now says who started the thread and when
(64af736c); the snapshot's room-name line is a pattern for that.
CI run 2104's Playwright job failed on this; the chromium suite passes
locally (19 passed, 3 skipped).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

e2e/a11y.spec.ts-snapshots/thread-panel.aria.yml

@@ -1,6 +1,6 @@
 - complementary "Thread":
     - paragraph: Thread
-    - paragraph: A11y Room
+    - paragraph: /A11y Room · started by e2e_a11y_\w+, .+/
     - button "Thread notifications":
         - img
     - button "Close thread":