fix(wizard,quotes,dates): reliable error routing, single-project accept, Persian date/time input

Wizard:
- failed saves now route to the exact step+field: a new data-field attribute on every required section (supplier_id, line_items, termsheets, project, quote_date, expiry_date, notes, proforma) plus resolveErrorTarget() that maps ApiError.field / message keywords (supplier, line item/material/unit/quantity, termsheet/schedule/milestone, project, dates, notes, file) to the offending step — the «رفع خطا» toast action scrolls/focuses the right control instead of guessing
- material records are no longer created on the fly while typing (rememberMaterial no longer fires addMaterial per blur); materials/specs/units are written once during the final save, avoiding half-created catalog rows

Accept flow:
- quote_service no longer rewrites LineItemProjects on accept — those candidate-project rows stay 100% untouched and only item_decisions.project_id is written, matching the per-item target-project model and the UI payload (item_projects: [])

Dates/time:
- JalaliDatePicker: hour/minute are now editable text fields (Persian digits, clamping, 3-digit retype handling) with a controlled useEffect that only rewrites the inputs when the numeric value actually changes — no more wiping in-progress typing; date-only detection tightened to a full YYYY-MM-DD match so datetime strings are not misread

Also: /api validation logging (RequestValidationError) now includes the path and error list for faster diagnosis.

Verified: api + frontend image builds (python, tsc, vite) clean on top of origin/production (incl. the team's mobile layout merges).

frontend/src/pages/Wizard/Step3Termsheets.tsx

@@ -47,7 +47,7 @@ export function Step3Termsheets({ cards, onCardsChange, items, coverage, onCover
       </h3>
       <div className="mb-3 text-[12px] text-muted" dangerouslySetInnerHTML={{ __html: 'هر <b>termsheet</b> یک روش پرداخت است (نقد، چک، اقساط...). داخل هر termsheet مشخص کنید کدام قلم‌ها را پوشش می‌دهد — یک termsheet می‌تواند چند قلم را بگیرد، و یک قلم هم می‌تواند زیر چند termsheet مختلف (مثلاً هم نقد هم چک) پیشنهاد شود.' }} />
 
-      <div className="flex flex-col gap-3">
+      <div data-field="termsheets" className="flex flex-col gap-3">
         {cards.map((card, idx) => (
           <TermsheetCard
             key={card.key}