feat(ui): modernize button design system and update Dashboard and Inventory pages

Frontend-only cherry-pick of prod_v2 3bdb05f; the dev compose
api port change (8000 -> 8001) is intentionally excluded.

frontend/src/pages/Dashboard/DashboardPage.tsx

@@ -1,6 +1,7 @@
 import { useMemo, useState } from "react";
 import { Link } from "react-router-dom";
 import { Users, FolderKanban, Ruler, Plus } from "lucide-react";
+import { Button } from "../../components/ui/button";
 import {
   useMaterials,
   useProjects,
@@ -80,22 +81,33 @@ export function DashboardPage() {
         menu={<AppSwitcherMenu activeModule="procurement" />}
         actions={
           <>
-            <Link to="/suppliers" className="btn-line-file no-underline">
-              <Users className="h-3.5 w-3.5" />
-              تأمین‌کننده‌ها
-            </Link>
-            <Link to="/projects" className="btn-line-file no-underline">
-              <FolderKanban className="h-3.5 w-3.5" />
-              پروژه‌ها
-            </Link>
-            <Link to="/units" className="btn-line-file no-underline">
-              <Ruler className="h-3.5 w-3.5" />
-              ضرایب تبدیل
-            </Link>
-            <Link to="/wizard" className="btn-line-file no-underline bg-accent text-white hover:bg-accent-dark">
-              <Plus className="h-3.5 w-3.5" />
-              افزودن پیشنهاد جدید
-            </Link>
+            <Button asChild variant="slate">
+              <Link to="/suppliers" className="no-underline">
+                <Users className="h-4 w-4" />
+                تأمین‌کننده‌ها
+              </Link>
+            </Button>
+
+            <Button asChild variant="slate">
+              <Link to="/projects" className="no-underline">
+                <FolderKanban className="h-4 w-4" />
+                پروژه‌ها
+              </Link>
+            </Button>
+
+            <Button asChild variant="line">
+              <Link to="/units" className="no-underline">
+                <Ruler className="h-4 w-4" />
+                ضرایب تبدیل
+              </Link>
+            </Button>
+
+            <Button asChild variant="primary">
+              <Link to="/wizard" className="no-underline">
+                <Plus className="h-4 w-4" />
+                افزودن پیشنهاد جدید
+              </Link>
+            </Button>
           </>
         }
       />
@@ -128,4 +140,4 @@ export function DashboardPage() {
       <EditModal quoteId={editId} onClose={() => setEditId(null)} />
     </div>
   );
-}
+}