Reuse shared base controls in MainNav and Integrations, add active integration icons, and keep compact integration content framing covered by targeted tests.
Update active main nav icon positioning from the refreshed Figma assets, remove the transparent active border that caused nav item jitter, and route mobile common layout through the new MainNav instead of the legacy Header.
Also align workspace plan actions with the new UI contract by showing Upgrade for sandbox workspaces and View Plan for paid workspaces, both opening the pricing modal.
- add the integrations page sidebar with collapsible icon-only navigation and Figma-aligned marketplace card
- move custom integration SVGs into the iconify collection and document the Tailwind i-custom workflow
- preserve source SVG collection dimensions when flattening generated icon data so existing main nav icons keep their 20x20 viewBox
- add an icon dimension guard for layout-sensitive generated icons
- update model provider routing, i18n, and focused frontend tests
