Webapp: Inbox, search, and knowledge stores

Chat renamed to Inbox. Full-text search and knowledge stores added to the webapp.

• Conversation count badge and status filters in the inbox
• Assignee visible on each conversation
• Conversations track state: open, pending, resolved
• Full-text search across all messages, customer names, and metadata
• Knowledge stores: create, edit, and delete support articles inside SupportWire
• Video attachments open in a lightbox with download and link copy
• Shared motion system for consistent animations and transitions
• Reduced re-renders and duplicate network requests