feat(browser): breadcrumb trail on errors, console forwarding to logs - #1151

Confidence 4/5 · likely safe to merge
The two files the kickoff lists as changed since the last review are not in this head's diff, so no new code was added to review.
_{quality 100/100 · no findings · tests covered · risk medium · 2/2 new units observable}

Adds an in-memory breadcrumb trail (clicks, inputs, navigations, console) exported as OTel logs linked to an error's span, plus logs.captureConsole forwarding. The head carries no code newer than the previous review; nothing new to object to.

• startBreadcrumbs keeps 50 crumbs and flushBreadcrumbs exports them on error
• onSessionEvent listener hook added to the browser-session sink
• logs.captureConsole forwards chosen console levels as logs
• installConsoleCapture teardown now only undoes its own wrapper

_{6b8ab64 · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple to ask about one.}