Harden práctica create/update/HC-fix actions against silent save failure (uncaught pool.connect + missing client try/catch)

PLUTO-678/SOP-11 investigation found createPractica/updatePractica/updateNumeroHistoriaClinica have no client-side try/catch around the server-action call (practica-form.tsx submitCreate ~553-577, practica-detail.tsx 104-116) and pool.connect() sits outside try in practica-actions.ts (lines 85, 871, 1168) — a connect failure/timeout throws uncaught, button stays stuck on Guardando with zero error toast and zero write. Confirmed live-correlated with the 2026-07-02 max-2 pool-exhaustion incident (PLUTO-471/472, commits 16222ec/3ac9222) same day as this ticket's silent-loss. Fix: wrap client calls in try/catch with generic error toast + setLoading(false) fallback; move each action's pool.connect() inside its own try so a connect-time failure returns {success:false} instead of throwing uncaught.