v1.16.2

v1.16.2 — email input width + alert storm suppression

Two issues caught by Nathan within minutes of v1.16.1's auto-update
rollout:

1. Email input field rendered narrower than the discord webhook field
   next to it. Root cause: CSS at static/style.css:2210 targeted
   input[type=\"text\"] only, not input[type=\"email\"]. Added the
   email selector to both the visual-styling rule and the flex-grow
   sizing rule.

2. Saving an email address fired alerts for EVERY currently-tripping
   miner immediately — Nathan got 5 emails the moment he hit save.
   Two paths produced this:

   a. App had JUST restarted into v1.16.1 (auto-update install), so
      the in-memory _alerts_last_fired dict was empty. First poll
      after that found 5 miners with tripping conditions, fired all 5.
      Fix: 60-second post-startup quiet window in
      _alerts_should_fire — first ALERTS_STARTUP_QUIET_S seconds
      record the trigger time but suppress the actual firing so the
      cooldown clock starts ticking from boot. After that the normal
      30-min cooldown applies.

   b. Adding a brand-new channel (going from empty → set) should
      pre-arm cooldowns so the new destination only sees alerts that
      trip from the moment of save forward. Otherwise every miner
      whose Discord webhook was already aware of an alert state
      double-pings the freshly-saved email. Fix: detect the empty→set
      transition in api_alerts_config_set + write \"now\" to every
      device's cooldown table.

Both fixes are conservative — they suppress the rare nuisance case
without dropping any legitimate alert. Worst case: 60 seconds of
silence after restart, then everything fires normally.