feat: add bulk delete, fix csv formatting, fix button hover UI

src/app/admin/students/page.tsx

@@ -4,7 +4,7 @@ import { fetchWithAuth } from "@/lib/apiClient";
 import { useEffect, useState } from "react"
 import { Badge } from "@/components/ui/badge"
 import { Button } from "@/components/ui/button"
-import { Search, Download, Flame, RefreshCw, Upload } from "lucide-react"
+import { Search, Download, Flame, RefreshCw, Upload, Trash2 } from "lucide-react"
 import { useRouter } from "next/navigation"
 import { useRef } from "react"
 
@@ -25,6 +25,8 @@ export default function StudentsPage() {
   const [students, setStudents] = useState<any[]>([])
   const [loading, setLoading] = useState(true)
   const [search, setSearch] = useState("")
+  const [selectedIds, setSelectedIds] = useState<string[]>([])
+  const [deleting, setDeleting] = useState(false)
 
   const fileInputRef = useRef<HTMLInputElement>(null)
   
@@ -45,17 +47,20 @@ export default function StudentsPage() {
       const results = await rawRes.json()
       alert(`Successfully registered ${results.length} students!`)
       
-      // Download CSV with passwords
+      // Download CSV with passwords using Blob to fix formatting on Windows
-      let csvContent = "data:text/csv;charset=utf-8,name,email,password\\n"
+      const csvRows = ["name,email,password"];
       results.forEach((row: any) => {
-        csvContent += `${row.name},${row.email},${row.password}\\n`
+        csvRows.push(`${row.name},${row.email},${row.password}`);
-      })
+      });
-      const encodedUri = encodeURI(csvContent)
+      const csvContent = csvRows.join("\r\n");
-      const link = document.createElement("a")
+      const blob = new Blob([csvContent], { type: 'text/csv;charset=utf-8;' });
-      link.setAttribute("href", encodedUri)
+      const url = URL.createObjectURL(blob);
-      link.setAttribute("download", "bulk_registered_passwords.csv")
+      const link = document.createElement("a");
-      document.body.appendChild(link)
+      link.setAttribute("href", url);
-      link.click()
+      link.setAttribute("download", "bulk_registered_passwords.csv");
+      document.body.appendChild(link);
+      link.click();
+      URL.revokeObjectURL(url);
       
       // Refresh students
       const fresh = await fetchWithAuth("/api/admin/students").then(r => r.json())
@@ -68,6 +73,29 @@ export default function StudentsPage() {
     }
   }
 
+  
+  const handleDeleteSelected = async () => {
+    if (!selectedIds.length) return
+    if (!confirm(`Are you sure you want to delete ${selectedIds.length} students? This cannot be undone.`)) return
+    
+    setDeleting(true)
+    try {
+      const res = await fetchWithAuth("/api/admin/students/bulk", {
+        method: "DELETE",
+        body: JSON.stringify({ user_ids: selectedIds })
+      })
+      if (!res.ok) throw new Error("Delete failed")
+      
+      setSelectedIds([])
+      const fresh = await fetchWithAuth("/api/admin/students").then(r => r.json())
+      setStudents(fresh)
+    } catch (err: any) {
+      alert("Error deleting students: " + err.message)
+    } finally {
+      setDeleting(false)
+    }
+  }
+
   const downloadTemplate = () => {
     const template = "data:text/csv;charset=utf-8,name,email,phone,target_exam,tier\\nJohn Doe,john@example.com,9876543210,JEE_Main,Free\\nJane Smith,jane@example.com,9876543211,NEET,Pro"
     const encodedUri = encodeURI(template)
@@ -107,14 +135,19 @@ export default function StudentsPage() {
           </p>
         </div>
         <div className="flex gap-2">
+          {selectedIds.length > 0 && (
+            <Button variant="destructive" disabled={deleting} onClick={handleDeleteSelected}>
+              <Trash2 size={16} className="mr-2" /> Delete ({selectedIds.length})
+            </Button>
+          )}
           <input type="file" accept=".csv" className="hidden" ref={fileInputRef} onChange={handleBulkUpload} />
-          <Button variant="outline" className="border-border hover:bg-secondary" onClick={() => fileInputRef.current?.click()}>
+          <Button variant="outline" className="border-border hover:bg-secondary hover:text-white" onClick={() => fileInputRef.current?.click()}>
             <Upload size={16} className="mr-2" /> Bulk Register CSV
           </Button>
-          <Button variant="outline" className="border-border hover:bg-secondary" onClick={downloadTemplate}>
+          <Button variant="outline" className="border-border hover:bg-secondary hover:text-white" onClick={downloadTemplate}>
             <Download size={16} className="mr-2" /> Download Template
           </Button>
-          <Button variant="outline" className="border-border hover:bg-secondary">
+          <Button variant="outline" className="border-border hover:bg-secondary hover:text-white">
             <Download size={16} className="mr-2" /> Export CSV
           </Button>
         </div>
@@ -143,6 +176,17 @@ export default function StudentsPage() {
             <table className="w-full text-left text-sm whitespace-nowrap">
               <thead className="bg-secondary/30 text-muted-foreground border-b border-border">
                 <tr>
+                  <th className="px-4 py-4 w-10">
+                    <input 
+                      type="checkbox" 
+                      className="rounded border-border bg-background"
+                      checked={filtered.length > 0 && selectedIds.length === filtered.length}
+                      onChange={(e) => {
+                        if (e.target.checked) setSelectedIds(filtered.map(s => s.id))
+                        else setSelectedIds([])
+                      }}
+                    />
+                  </th>
                   <th className="px-6 py-4 font-semibold">Student</th>
                   <th className="px-6 py-4 font-semibold">Plan</th>
                   <th className="px-6 py-4 font-semibold">Target</th>
@@ -159,6 +203,17 @@ export default function StudentsPage() {
                     className="hover:bg-secondary/20 transition-colors cursor-pointer"
                     onClick={() => router.push(`/admin/students/${s.id}`)}
                   >
+                    <td className="px-4 py-4 w-10" onClick={(e) => e.stopPropagation()}>
+                      <input 
+                        type="checkbox" 
+                        className="rounded border-border bg-background"
+                        checked={selectedIds.includes(s.id)}
+                        onChange={(e) => {
+                          if (e.target.checked) setSelectedIds([...selectedIds, s.id])
+                          else setSelectedIds(selectedIds.filter(id => id !== s.id))
+                        }}
+                      />
+                    </td>
                     <td className="px-6 py-4">
                       <div className="flex items-center gap-3">
                         <div className="w-8 h-8 rounded-full bg-secondary flex items-center justify-center text-xs font-bold shrink-0">