Improve convert-to-trade security selection with search-first UX (#703)

* Enhance security handling logic:
- Prioritize user's country in sorting securities and country codes.
- Add comprehensive mapping for MIC codes to user-friendly exchange names.
- Revamp combobox to consistently pull from a provider when available.
- Improve handling of custom ticker and exchange input fields.

* Localize securities combobox display and exchange labels.

---------

Co-authored-by: luckyPipewrench <luckypipewrench@proton.me>

app/models/security/provided.rb

@@ -21,7 +21,7 @@ module Security::Provided
       response = provider.search_securities(symbol, **params)
 
       if response.success?
-        response.data.map do |provider_security|
+        securities = response.data.map do |provider_security|
           # Need to map to domain model so Combobox can display via to_combobox_option
           Security.new(
             ticker: provider_security.symbol,
@@ -31,6 +31,19 @@ module Security::Provided
             country_code: provider_security.country_code
           )
         end
+
+        # Sort results to prioritize user's country if provided
+        if country_code.present?
+          user_country = country_code.upcase
+          securities.sort_by do |s|
+            [
+              s.country_code&.upcase == user_country ? 0 : 1, # User's country first
+              s.ticker.upcase == symbol.upcase ? 0 : 1        # Exact ticker match second
+            ]
+          end
+        else
+          securities
+        end
       else
         []
       end