feat: initialize thoughts-frontend with Next.js, TypeScript, and ESLint

- Add ESLint configuration for Next.js and TypeScript support.
- Create Next.js configuration file with standalone output option.
- Initialize package.json with scripts for development, build, and linting.
- Set up PostCSS configuration for Tailwind CSS.
- Add SVG assets for UI components.
- Create TypeScript configuration for strict type checking and module resolution.

thoughts-backend/api/src/extractor/json.rs

@@ -0,0 +1,26 @@
+use axum::{
+    extract::FromRequest,
+    response::{IntoResponse, Response},
+};
+use validator::Validate;
+
+use crate::error::ApiError;
+
+#[derive(FromRequest)]
+#[from_request(via(axum::Json), rejection(ApiError))]
+pub struct Json<T>(pub T);
+
+impl<T> IntoResponse for Json<T>
+where
+    axum::Json<T>: IntoResponse,
+{
+    fn into_response(self) -> Response {
+        axum::Json(self.0).into_response()
+    }
+}
+
+impl<T: Validate> Validate for Json<T> {
+    fn validate(&self) -> Result<(), validator::ValidationErrors> {
+        self.0.validate()
+    }
+}

thoughts-backend/api/src/extractor/mod.rs

@@ -0,0 +1,5 @@
+mod json;
+mod valid;
+
+pub use json::Json;
+pub use valid::Valid;

thoughts-backend/api/src/extractor/valid.rs

@@ -0,0 +1,23 @@
+use axum::extract::{FromRequest, Request};
+use validator::Validate;
+
+use crate::validation::ValidRejection;
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Valid<T>(pub T);
+
+impl<State, Extractor> FromRequest<State> for Valid<Extractor>
+where
+    State: Send + Sync,
+    Extractor: Validate + FromRequest<State>,
+{
+    type Rejection = ValidRejection<<Extractor as FromRequest<State>>::Rejection>;
+
+    async fn from_request(req: Request, state: &State) -> Result<Self, Self::Rejection> {
+        let inner = Extractor::from_request(req, state)
+            .await
+            .map_err(ValidRejection::Extractor)?;
+        inner.validate()?;
+        Ok(Valid(inner))
+    }
+}