fix(tui): stop perf-buffer leak and react to terminal resize

[admarble]

Two fixes for the sequant run dashboard.

1. perf_hooks leak (MaxPerformanceEntryBufferExceededWarning)

ink pulls in react-reconciler, which loads its development bundle whenever NODE_ENV !== "production" (the normal dogfooding case). That bundle emits an uncleared performance.measure() per component render; driven by the TUI's 10 Hz poll it overflows Node's ~1,000,000-entry global perf buffer and writes a raw warning to stderr — which also corrupts the in-place redraw (stderr scrolls the terminal between frames, so the erase undershoots and frames stack).

Fix: new src/ui/tui/load.ts — loadTui() brackets the TUI's single dynamic import() with NODE_ENV=production (only when unset), caching the production reconciler (zero performance.measure calls), then restores NODE_ENV so spawned phase children don't inherit it (e.g. npm install skipping devDependencies). Both call sites (run.ts, ready.ts) now go through it.

Verified: same render workload went from 206 → 0 measure entries; NODE_ENV confirmed restored afterward.

2. Width corruption on resize (duplicate / garbled frames)

ink's resize handler re-renders the existing React tree but does not re-run App, and App read stdout.columns imperatively — so after a resize it repainted boxes at the stale, too-wide width until the next 100 ms poll. Those over-wide lines wrapped while short lines didn't, misaligning the box borders into the garbled/duplicate frames.

Fix (App.tsx): track columns in state, updated from the stdout resize event (plus a 1 Hz fallback for terminals that don't emit it), and clamp boxWidth to the live width.

Tests

• load.test.ts — pins the NODE_ENV restore behavior for every prior state.
• App.resize.test.ts — renders a real ink tree, shrinks 120 → 60, and asserts the box width follows within one frame (under the poll). Confirmed it fails on the un-fixed code and passes with the fix.

typecheck clean; 224 tests pass in the touched areas.