Add global sync summary component for all providers (#588)

* Add shared sync statistics collection and provider sync summary UI

- Introduced `SyncStats::Collector` concern to centralize sync statistics logic, including account, transaction, holdings, and health stats collection.
- Added collapsible `ProviderSyncSummary` component for displaying sync summaries across providers.
- Updated syncers (e.g., `LunchflowItem::Syncer`) to use the shared collector methods for consistent stats calculation.
- Added rake tasks under `dev:sync_stats` for testing and development purposes, including fake stats generation with optional issues.
- Enhanced provider-specific views to include sync summaries using the new shared component.

* Refactor `ProviderSyncSummary` to improve maintainability

- Extracted `severity_color_class` to simplify severity-to-CSS mapping.
- Replaced `holdings_label` with `holdings_label_key` for streamlined localization.
- Updated locale file to separate `found` and `processed` translations for clarity.

---------

Signed-off-by: Juan José Mata <juanjo.mata@gmail.com>
Co-authored-by: Josh Waldrep <joshua.waldrep5+github@gmail.com>
Co-authored-by: Juan José Mata <juanjo.mata@gmail.com>

app/views/plaid_items/_plaid_item.html.erb

@@ -80,7 +80,20 @@
       <div class="space-y-4 mt-4">
         <% if plaid_item.accounts.any? %>
           <%= render "accounts/index/account_groups", accounts: plaid_item.accounts %>
-        <% else %>
+        <% end %>
+
+        <%# Sync summary (collapsible) - using shared ProviderSyncSummary component %>
+        <% stats = if defined?(@plaid_sync_stats_map) && @plaid_sync_stats_map
+             @plaid_sync_stats_map[plaid_item.id] || {}
+           else
+             plaid_item.syncs.ordered.first&.sync_stats || {}
+           end %>
+        <%= render ProviderSyncSummary.new(
+          stats: stats,
+          provider_item: plaid_item
+        ) %>
+
+        <% if plaid_item.accounts.empty? %>
           <div class="p-4 flex flex-col gap-3 items-center justify-center">
             <p class="text-primary font-medium text-sm"><%= t(".no_accounts_title") %></p>
             <p class="text-secondary text-sm"><%= t(".no_accounts_description") %></p>