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.
Add a Bun script to apply and normalize AGPL copyright headers across the default frontend source files.
The script keeps headers idempotent, upgrades existing headers to the 2023-2026 QuantumNous range, and is exposed through `bun run copyright` for future maintenance.
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