v2 Phase 0 — Quick wins (touch targets, breakpoints, roomier text editor)

[szrudi]

Umbrella issue for Phase 0 of the v2 UI overhaul: small, real wins that establish foundations the later mobile-first slices will lean on. No architectural change here — these are the cheap, high-value fixes.

Slices

0.1 — Roomier text editor + variable hint

• Bump TextWidgetEditor textarea to rows={3} minimum with field-sizing: content (auto-grow).
• Add a subtle helper line listing detected variables for that widget (seeds variable awareness ahead of templates in Phase 2).
• Widen the scale input.
• Done when: a 3-line label typed in a phone-width window shows all 3 lines without internal scroll.

0.2 — Tailwind breakpoint baseline

• Introduce sm: and md: usage in App.tsx and a short comment in index.css documenting intent.
• No visual change yet — establishes the grid every later mobile slice will reach for.
• Done when: at least two of sm: / md: / lg: are referenced; visual regression set unchanged.

0.3 — Touch-target audit

• Raise .btn and .input minimum hit area to 44 px effective height on touch.
• Apply to the small ✕ delete, drag handle ⠿, EyeIcon (14×14) in BatchPanel, refresh ↻.
• Keep desktop density via responsive padding.
• Done when: Lighthouse mobile + manual check shows nothing below 44×44 CSS px.

Phase exit criteria

All three slices merged, npm test green, mobile smoke at 390×844 looks usably tappable.