Create a flat table view for identities matching the API keys pattern, with the ability to view details and create new identities with metadata (preserving existing functionality).

Acceptance Criteria

List View & Table

•  Flat table view with columns:
  • External ID (plain text, truncate if >50 chars with ...)
  • Identity ID (truncated using shortenId() helper)
  • Number of keys associated
  • Number of ratelimits
  • Created date
  • Last used timestamp (from ClickHouse analytics if available)
•  Hover over truncated identity ID shows full ID in tooltip
•  Search/filter bar for external ID search
•  Cursor-based pagination (50 items per page)
•  Empty state when no identities exist with "Create Identity" CTA
•  Loading skeleton states during data fetch
•  Responsive design matching dashboard patterns
•  Hover states on table rows
•  Click on row navigates to identity detail page

Context Menu

•  Context menu (3-dot) on each row with:
  • Copy identity ID (with toast notification)
  • Copy external ID (with toast notification)

Create Identity (Existing Functionality)

•  "Create Identity" button in page header
•  Dialog/form opens with fields:
  • External ID (text input, required, 3-255 characters)
  • Metadata (JSON editor, optional, <1MB)
•  External ID validation:
  • Cannot be only whitespace
  • Shows error if duplicate exists
•  Metadata validation:
  • Valid JSON syntax
  • Size limit validation
•  Success toast: "Identity created successfully"
•  Table updates optimistically with new identity
•  Error handling for duplicate external IDs (409 conflict)
•  Cancel button closes dialog without creating

Technical Notes

• Reuse existing create identity logic from trpc.identity.create
• Table components from apps/dashboard/app/(app)/[workspaceSlug]/apis/[apiId]/keys/[keyAuthId]/_components/components/table/
• Use trpc.identity.query for list data
• Use shortenId() helper from @/lib/shorten-id for identity ID display