feat: implement label management with color filtering

keep-notes/app/api/labels/route.ts

@@ -1,24 +1,16 @@
 import { NextRequest, NextResponse } from 'next/server'
 import prisma from '@/lib/prisma'
 
-// GET /api/labels - Get all unique labels
+// GET /api/labels - Get all labels
 export async function GET(request: NextRequest) {
   try {
-    const notes = await prisma.note.findMany({
-      select: { labels: true }
-    })
-
-    const labelsSet = new Set<string>()
-    notes.forEach(note => {
-      const labels = note.labels ? JSON.parse(note.labels) : null
-      if (labels) {
-        labels.forEach((label: string) => labelsSet.add(label))
-      }
+    const labels = await prisma.label.findMany({
+      orderBy: { name: 'asc' }
     })
 
     return NextResponse.json({
       success: true,
-      data: Array.from(labelsSet).sort()
+      data: labels
     })
   } catch (error) {
     console.error('GET /api/labels error:', error)
@@ -28,3 +20,48 @@ export async function GET(request: NextRequest) {
     )
   }
 }
+
+// POST /api/labels - Create a new label
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.json()
+    const { name, color } = body
+
+    if (!name || typeof name !== 'string') {
+      return NextResponse.json(
+        { success: false, error: 'Label name is required' },
+        { status: 400 }
+      )
+    }
+
+    // Check if label already exists
+    const existing = await prisma.label.findUnique({
+      where: { name: name.trim() }
+    })
+
+    if (existing) {
+      return NextResponse.json(
+        { success: false, error: 'Label already exists' },
+        { status: 409 }
+      )
+    }
+
+    const label = await prisma.label.create({
+      data: {
+        name: name.trim(),
+        color: color || 'gray'
+      }
+    })
+
+    return NextResponse.json({
+      success: true,
+      data: label
+    })
+  } catch (error) {
+    console.error('POST /api/labels error:', error)
+    return NextResponse.json(
+      { success: false, error: 'Failed to create label' },
+      { status: 500 }
+    )
+  }
+}