refactor: convert auth register to Server Action

- Add src/app/actions/auth.ts with registerUser
- Update RegisterForm to use Server Action
- Remove api/auth/register route

src/app/api/auth/register/route.ts

@@ -1,55 +0,0 @@
-import { NextRequest, NextResponse } from "next/server";
-import { AuthServerService } from "@/lib/services/auth-server.service";
-import { ERROR_CODES } from "@/constants/errorCodes";
-import { ERROR_MESSAGES } from "@/constants/errorMessages";
-import { AppError } from "@/utils/errors";
-import logger from "@/lib/logger";
-
-export async function POST(request: NextRequest) {
-  try {
-    const { email, password } = await request.json();
-
-    if (!email || !password) {
-      return NextResponse.json(
-        {
-          error: {
-            code: ERROR_CODES.AUTH.INVALID_USER_DATA,
-            name: "Invalid user data",
-            message: ERROR_MESSAGES[ERROR_CODES.AUTH.INVALID_USER_DATA],
-          } as AppError,
-        },
-        { status: 400 }
-      );
-    }
-
-    const userData = await AuthServerService.registerUser(email, password);
-
-    return NextResponse.json({ success: true, user: userData });
-  } catch (error) {
-    logger.error({ err: error }, "Registration error:");
-
-    if (error instanceof AppError) {
-      return NextResponse.json(
-        {
-          error: {
-            code: error.code,
-            name: error.name,
-            message: error.message,
-          } as AppError,
-        },
-        { status: 400 }
-      );
-    }
-
-    return NextResponse.json(
-      {
-        error: {
-          code: ERROR_CODES.AUTH.REGISTRATION_FAILED,
-          name: "Registration failed",
-          message: ERROR_MESSAGES[ERROR_CODES.AUTH.REGISTRATION_FAILED],
-        } as AppError,
-      },
-      { status: 500 }
-    );
-  }
-}