Reapply workspace type tags (#113)

[rawkintrevo]

Summary

• Reapply the workspace type tag UI from the lost Show workspace type tags instead of workspace/session-id metadata #113/feat: show workspace type tags instead of workspace/session-id metadata (#113) #119 work after main was reset.
• Show Blank/GitHub/Dev machine badges in workspace rows and the selected workspace header.
• Hide storage/session-prefix metadata from primary non-GitHub workspace summaries.
• Add unit coverage for workspace tag and summary behavior.
• Update the frontend developer wiki note for the workspace tag owner.

Tests

• npm run test:frontend
• npm run build
• npm run docs:check

QA

• Browser QA skipped at user request.

Refs #113

[github-actions]

Visit the preview URL for this PR (updated for commit c138f3d):

https://pi-agents-cloud--pr121-113-show-workspace-t-4hrvp6ka.web.app

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