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/Dashboard/AcceptModal.tsx

@@ -219,20 +219,14 @@ export function AcceptModal({ quoteId, onClose }: AcceptModalProps) {
       if (t.status === "accepted" && !usedIds.has(t.id)) t.status = "offered";
     });
 
-    // پروژه‌ی هر قلم (تکی هدف خرید) + همگام‌سازی پروژه‌های سطح پیشنهاد
-    const projUnion = new Set<string>();
+    // پروژه‌ی هر قلم (تکی هدف خرید) — فقط target_project تنظیم می‌شود؛
+    // li.projects و next.projects دست‌نخورده باقی می‌مانند تا پروژه‌های کاندیدای اولیه حفظ شوند
     next.line_items.forEach((li) => {
       if (li.rejected) return;
       const name = itemProjectsSel[li.id];
       if (name === undefined) return;
       li.target_project = name ? { id: "", name } : null;
-      // توجه: li.projects دست‌نخورده باقی می‌ماند تا پروژه‌های کاندیدای اولیه حفظ شوند
-      if (name) projUnion.add(name);
     });
-    if (projUnion.size > 0) {
-      next.projects = [...projUnion];
-      next.project = next.projects[0] || "";
-    }
 
     const now = new Date().toISOString();
     next.accepted_date = acceptDate || now;