Promotion dropdown builds a /alerts/rules/new URL with promoteFrom, ruleId,
and targetEnv query params — the wizard will read these in Task 24 and
pre-fill the form with source-env prefill + client-side warnings.
AlertRow is reused by AllAlertsPage and HistoryPage. Marking a row as read
happens when its link is followed (the detail sub-route will be added in
phase 10 polish). FIRING rows get an amber left border.
Adds 6 lazy-loaded route entries for the alerting UI (Inbox, All, History,
Rules list, Rule editor wizard, Silences) plus an `/alerts` → `/alerts/inbox`
redirect. Page components are placeholder stubs to be replaced in Phase 5/6/7.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
