revert(settings/providers): drop the slim health strip

Per-row status pills already carry the at-a-glance signal (connected
/ action needed) at the scale this app sees (1–4 connections per
family). The strip was redundant chrome for almost every user; only
worth bringing back if the catalog grows to a point where the row
list itself stops fitting on a single screen.

- Delete _health_strip.html.erb partial.
- Drop @health controller assignment + provider_health_strip helper.
- Drop unused settings.providers.health_strip.* locale keys.
- concise_time_ago helper stays — still used by per-row meta text.

app/controllers/settings/providers_controller.rb

@@ -261,8 +261,6 @@ class Settings::ProvidersController < ApplicationController
       @connected        = entries.select { |e| e[:summary][:status] == :ok }
       @needs_attention  = entries.select { |e| [ :warn, :err ].include?(e[:summary][:status]) }
       @available        = entries.select { |e| e[:summary][:status] == :off }
-
-      @health = view_context.provider_health_strip(connected: @connected, needs_attention: @needs_attention)
     end
 
     # Returns a hash mapping provider key → { error:, last_synced_at:, stale: }