✨ refactor: system settings UI for consistent, compact layouts

Redesign the system settings interface to align with the rest of the console experience by using fixed header actions, removing redundant subtitles, respecting global content width, and standardizing responsive form layouts.

Introduce reusable settings layout primitives for forms, switch rows, grouped controls, nested control sections, title status indicators, and page action portals. Replace duplicated card-style switch markup with explicit compact components, improve nested switch readability, and reduce visual noise across authentication, billing, content, integrations, maintenance, models, and request-limit settings.

Also complete missing i18n translations, remove obsolete subtitle translation keys, refine i18n sync reporting, fix sidebar truncation for long labels, and verify the frontend with type checking and lint diagnostics.

web/default/src/i18n/static-keys.ts

@@ -202,7 +202,6 @@ export const STATIC_I18N_KEYS = [
 
   // Channel Affinity section
   'Channel Affinity',
-  'Configure channel affinity (sticky routing) rules',
 
   // Models constants
   'Exact Match',
@@ -340,7 +339,6 @@ export const STATIC_I18N_KEYS = [
 
   // Subscription management
   'Subscription Management',
-  'Manage subscription plan creation, pricing and status',
   'Stripe/Creem requires creating products on the third-party platform and entering the ID',
   'Create Plan',
   'Active',
@@ -457,7 +455,6 @@ export const STATIC_I18N_KEYS = [
 
   // Grok settings
   'Grok Settings',
-  'Configure xAI Grok model specific settings',
   'Enable violation deduction',
   'When enabled, violation requests will incur additional charges.',
   'Official documentation',