Diagnosis and phased plan for the board's lag, grounded in the codebase:
the dominant cause is a render storm (orchestrator state hoisted at the
top, every SSE event re-renders all cards; KanbanCard not memoized), plus
a 3s background poll, an N+1 on /board, and per-card status scans.
Covers four phases — memoize (now landed in 292005e), calm the poll, batch
the /board query, and small wins — with a measurement plan and risk notes.
EOF && echo "" && git log --oneline -3
