feat(i18n): extract hardcoded English strings to locale files (#1806)

* Extract hardcoded strings to i18n

Replace numerous hardcoded English strings with I18n lookups (t / I18n.t) across controllers, views, helpers, and components, and convert model validation error messages to symbol keys. Added multiple locale files under config/locales for models and views. This centralizes user-facing notices/alerts, UI text, import/validation messages, and prepares the app for localization and easier translation maintenance.

* Update en.yml

* Update preview-cleanup.yml

* Revert "Update preview-cleanup.yml"

This reverts commit 1ba6d3c34c.

* test: align i18n assertions with translated messages

* Standardize balance error key and tweak locales

Replace SophtronAccount's :requires_balance error key with :no_balance and update related locale strings for sophtron, plaid, and simplefin accounts to use the new key and clearer copy. Also switch the QIF upload redirect notice to use a relative translation key (t('.qif_uploaded')), remove an unused SSO providers help line, and fix a trailing-newline/whitespace issue in the subscriptions locale. These changes standardize validation keys and improve translation consistency and messaging.

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Co-authored-by: KiloClaw <kiloclaw@openclaw.ai>

app/controllers/settings/api_keys_controller.rb

@@ -31,7 +31,7 @@ class Settings::ApiKeysController < ApplicationController
     existing_keys.each { |key| key.update_column(:revoked_at, Time.current) }
 
     if @api_key.save
-      flash[:notice] = "Your API key has been created successfully"
+      flash[:notice] = t(".success")
       redirect_to settings_api_key_path
     else
       # Restore existing keys if new key creation failed
@@ -42,13 +42,13 @@ class Settings::ApiKeysController < ApplicationController
 
   def destroy
     if @api_key.nil?
-      flash[:alert] = "API key not found"
+      flash[:alert] = t(".not_found")
     elsif @api_key.demo_monitoring_key?
-      flash[:alert] = "This API key cannot be revoked"
+      flash[:alert] = t(".cannot_revoke")
     elsif @api_key.revoke!
-      flash[:notice] = "API key has been revoked successfully"
+      flash[:notice] = t(".revoked_successfully")
     else
-      flash[:alert] = "Failed to revoke API key"
+      flash[:alert] = t(".revoke_failed")
     end
     redirect_to settings_api_key_path
   end