refactor: migrate API from GraphQL to REST (TypeSpec/OpenAPI)

Replace the entire GraphQL stack (gqlgen, urql, graphql-codegen) with a
TypeSpec → OpenAPI 3.x pipeline using oapi-codegen for Go server stubs
and openapi-fetch + openapi-typescript for the frontend client.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/backend/api/handler_auth.go b/backend/api/handler_auth.go
new file mode 100644
index 0000000..6e10538
--- /dev/null
+++ b/backend/api/handler_auth.go
@@ -0,0 +1,73 @@
+package api
+
+import (
+	"context"
+	"database/sql"
+	"strconv"
+
+	"undef.ninja/x/feedaka/auth"
+	appcontext "undef.ninja/x/feedaka/context"
+)
+
+func (h *Handler) AuthLogin(ctx context.Context, request AuthLoginRequestObject) (AuthLoginResponseObject, error) {
+	user, err := h.Queries.GetUserByUsername(ctx, request.Body.Username)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return AuthLogin401JSONResponse{Message: "invalid credentials"}, nil
+		}
+		return AuthLogin401JSONResponse{Message: "invalid credentials"}, nil
+	}
+
+	if !auth.VerifyPassword(user.PasswordHash, request.Body.Password) {
+		return AuthLogin401JSONResponse{Message: "invalid credentials"}, nil
+	}
+
+	echoCtx := getEchoContext(ctx)
+	if echoCtx == nil {
+		return nil, errNoEchoContext
+	}
+
+	if err := h.SessionConfig.SetUserID(echoCtx, user.ID); err != nil {
+		return nil, err
+	}
+
+	return AuthLogin200JSONResponse{
+		User: User{
+			Id:       strconv.FormatInt(user.ID, 10),
+			Username: user.Username,
+		},
+	}, nil
+}
+
+func (h *Handler) AuthLogout(ctx context.Context, _ AuthLogoutRequestObject) (AuthLogoutResponseObject, error) {
+	echoCtx := getEchoContext(ctx)
+	if echoCtx == nil {
+		return nil, errNoEchoContext
+	}
+
+	if err := h.SessionConfig.DestroySession(echoCtx); err != nil {
+		return nil, err
+	}
+
+	return AuthLogout204Response{}, nil
+}
+
+func (h *Handler) AuthGetCurrentUser(ctx context.Context, _ AuthGetCurrentUserRequestObject) (AuthGetCurrentUserResponseObject, error) {
+	userID, ok := appcontext.GetUserID(ctx)
+	if !ok {
+		return AuthGetCurrentUser401JSONResponse{Message: "authentication required"}, nil
+	}
+
+	user, err := h.Queries.GetUserByID(ctx, userID)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return AuthGetCurrentUser401JSONResponse{Message: "authentication required"}, nil
+		}
+		return nil, err
+	}
+
+	return AuthGetCurrentUser200JSONResponse{
+		Id:       strconv.FormatInt(user.ID, 10),
+		Username: user.Username,
+	}, nil
+}