fix(crawler): narrow browser-dead heuristic to typed downcasts (0.36.7)

anyhow_looks_browser_dead substring-matched any chain message
containing channel / connection / websocket / transport / closed /
nav timeout. Real chromium failures hit those words, but so do
reqwest TCP-reset errors during CDN image downloads, sqlx pool-
timeout errors, and any number of non-browser failures — each of
which triggered a wasted chromium relaunch + session-probe re-run
against the catalog's rate-limit budget.

Drop the substring pass. Walk the chain looking only for typed
NavError (flagged via is_likely_browser_dead) or CdpError. Every
place we feed a chromium error into anyhow goes through one of
those types, so the typed downcasts cover the real cases without
the false-positive surface.

NavError::is_likely_browser_dead also drops its own substring
check on Cdp(e); any CdpError surfacing at the navigation layer
means the chromium-facing channel is the failing layer.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.36.6",
+  "version": "0.36.7",
   "private": true,
   "type": "module",
   "scripts": {