fix(tui): filter only connected workspaces in dialog

[jlongster]

Summary

• Keep the Warp dialog's recent workspace choices focused on connected workspaces so users don't pick stale or unusable entries.
• Dedupe recent workspace suggestions by workspace ID before limiting the list, so repeated sessions don't hide other valid recent workspaces.
• Add focused coverage for missing, inactive, duplicate, and connected workspace selection behavior.

Tests

• bun test test/cli/cmd/tui/dialog-workspace-create.test.ts
• bun typecheck