feat: complete candle annotator implementation

- Created CandleChart component with lightweight-charts integration
- Implemented SvgOverlay component for line drawing
- Integrated all components in main page
- Fixed TypeScript and Tailwind CSS compatibility issues
- Added comprehensive README.md with project documentation
- Created DEPLOYMENT.md with setup and troubleshooting guide
- Downgraded to stable versions (Tailwind v3, lightweight-charts v4)
- All 59 tasks from OpenSpec completed

src/app/api/upload/route.ts

@@ -3,7 +3,7 @@ import Papa from 'papaparse';
 import { db } from '@/lib/db';
 import { candles } from '@/lib/db/schema';
 
-export async function POST(request: NextRequest) {
+export async function POST(request: NextRequest): Promise<NextResponse> {
   try {
     const formData = await request.formData();
     const file = formData.get('file') as File;
@@ -17,7 +17,7 @@ export async function POST(request: NextRequest) {
 
     const text = await file.text();
 
-    return new Promise((resolve) => {
+    return new Promise<NextResponse>((resolve) => {
       Papa.parse(text, {
         header: true,
         dynamicTyping: true,
@@ -115,7 +115,7 @@ export async function POST(request: NextRequest) {
             );
           }
         },
-        error: (error) => {
+        error: (error: any) => {
           resolve(
             NextResponse.json(
               { error: `CSV parsing error: ${error.message}` },