PostHog 3000 navigation steps

[Twixes]

PostHog 3000 TODO

These are the next steps to work on. Inspired by PostHog/meta#81. Based on the PostHog 3000 project.
Goal: launch.

Navigation

• support infinite loading of paginated collections feat(3000): Add automatic "Load more" #15863
• support client-side search feat(3000): Add sidebar search #15191
• support server-side search feat(3000): Support server-side search of insights and groups #15818
• support keyboard navigation in the sidebar
• access dashboards from the sidebar
• access event definitions from the sidebar feat(3000): Add Data Management to the sidebar #16003
• access property definitions from the sidebar feat(3000): Add Data Management to the sidebar #16003
• access actions from the sidebar feat(3000): Add Data Management to the sidebar #16003
• access persons from the sidebar
• access groups from the sidebar
  • upsell
• access event explorer from the sidebar
• access insights from the sidebar
  • favorite insights
  • access insights history
• access recordings from the sidebar
• access feature flags from the sidebar
• access experiments from the sidebar feat(3000): Add experiments to the sidebar #16086
• access annotations from the sidebar feat(3000): Add annotations to the sidebar #16051
• access apps from the sidebar
• access project settings from the sidebar
• launch Toolbar from the sidebar feat(3000): Add sites sidebar for Toolbar launching #16389
• rename items from the sidebar feat(3000): Rename items directly in sidebar #15780 feat(3000): Allow renaming cohorts and insights #15843
• create items from the sidebar feat(3000): Create new items from sidebar #16614
• show item-level keyboard shortcuts in menus
• show scene-level keyboard shortcuts in the command palette
• allow customizing item sort order from list header
• show scene-dependent top bar "More" menu
• show scene-dependent top bar actions
• fix keyboard navigation

Features that are lower priority:

• access notebooks from the sidebar
• access database schema from the sidebar
• access early access features from the sidebar
• access surveys from the sidebar
• access web performance from the sidebar
• access ingestion warnings from the sidebar
• add "Open list in page"

Icons

• implement Central icons in the sidebar style(3000): Use new Central icons #16463
• implement those icons elsewhere (¡undefined scope!)

Theming

• add hover and active state colors for dark and light mode
• go through the UI and update colors to always be theme-dependent (e.g. remove --white) chore(3000): Fix dark mode colors #16108