feat(ui): Claude Teams UI parity follow-up (SYM-43)

[tmustier]

Summary

Claude Teams UI parity follow-up (SYM-43). Addresses the research findings from .research/claude-teams-ui-parity.md.

Changes

High-impact UI improvement: in-progress task visibility + stable widget height

Widget (teams-widget.ts):

• Add active column showing in-progress task count per worker (previously only pending + completed shown — in-progress tasks were invisible in counts)
• Fix total percentage to include all task states in denominator (was: completed/(pending+completed), now: completed/total)
• Rename columns: complete → done for consistency with task view terminology
• Show active task ID inline (#3) instead of sub-line — stabilizes widget height (no dynamic extra rows per worker)

Panel (teams-panel.ts):

• Same in-progress count and percentage fixes
• Same column rename (complete → done)
• Keeps active task sub-line in panel overview (more space available in interactive mode)

Documentation triage

docs/claude-parity.md:

• Add SYM-43 triage table mapping each research gap to its resolution status
• Mark deferred items (compact collapsed mode, display mode cycling) with rationale
• Update widget liveliness and interaction UX sections

README.md:

• Document per-worker task progress display (pending/active/done)
• Document inline active task ID in persistent widget

Before/After

Before (widget):

 ◉ Teammate alice  streaming  3m12s  · 0 pending · 1 complete · 5.2k tokens  reading…
     └ #3 Fix failing tests

After (widget):

 ◉ Teammate alice  streaming #3  3m12s  · 0 pending · 1 active · 1 done · 5.2k tokens  reading…

Key improvements:

• In-progress tasks now visible at a glance (the active column)
• Widget height is stable (no per-worker sub-lines)
• Active task ID inline after status
• Total % includes all task states

Verification

• npm run check passes (typecheck + lint)
• npm run smoke-test passes (325/325)
• No new test needed (rendering changes are visual; existing smoke tests verify data model)

Acceptance criteria

• UI parity deltas from research are triaged into concrete sub-tasks (see docs/claude-parity.md triage table)
• At least one high-impact UI parity improvement merged (in-progress count + stable height + percentage fix)
• Cleanup/done workflow is documented and testable (already done in prior PRs; verified in README)
• README reflects updated UI behavior and shortcuts

Closes SYM-43