Don't crash bootstrap on Matrix token capture failure

If chat.reddit.com sniffing fails, fall through with a placeholder
credential set so the post-monitoring/processor side of the bot
(and the web UI) stay up. Chat features are disabled until the
next successful token refresh.

Also dump diagnostics on sniff timeout: final page URL, every host
the page touched (with request counts + whether any carried an
Authorization header), and a full-page screenshot to data/matrix-debug.png.
This makes the three failure modes (page didn't load / loaded but
never hit Matrix / hit Matrix without auth) distinguishable from logs.

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

src/bootstrap.ts

@@ -147,10 +147,28 @@ export async function bootstrap(config: Config, logger: Logger): Promise<AppCont
   // ---- Matrix chat backend (replaces the Playwright scraper) ----
   // 1. Get credentials: prefer cached, fall back to a fresh sniff via the
   //    persistent browser session that we just verified is logged in.
+  //    If the sniff fails (e.g. egress blocked, chat.reddit.com refuses to
+  //    load), we *don't* crash bootstrap — the post-monitoring/processor
+  //    side of the bot doesn't need Matrix, and keeping the web UI up makes
+  //    the situation diagnosable. Chat calls will fail with 401 until a
+  //    subsequent token refresh succeeds.
   let matrixCreds: MatrixCredentials | null = await loadCachedCredentials();
   if (!matrixCreds) {
     logger.info('No cached Matrix credentials — extracting via browser session...');
-    matrixCreds = await extractMatrixCredentials(browserClient.getContext()!, logger);
+    try {
+      matrixCreds = await extractMatrixCredentials(browserClient.getContext()!, logger);
+    } catch (err) {
+      logger.error(
+        '[matrix] credential extraction failed — chat features will be disabled until the next successful refresh:',
+        err,
+      );
+      matrixCreds = {
+        homeserver: 'https://matrix.redditspace.com',
+        accessToken: '',
+        userId: '',
+        capturedAt: Date.now(),
+      };
+    }
   } else {
     logger.info(`Loaded cached Matrix credentials (user=${matrixCreds.userId})`);
   }