bug: Fix logout backend response and docker build

Dockerfile

@@ -18,7 +18,7 @@ RUN npm ci --no-audit --no-fund
 # outDir is "server/public", so output lands at /ui/server/public here.
 FROM ui-deps AS ui-build
 WORKDIR /ui
-COPY openapi.json orval.config.ts index.html vite.config.ts ./
+COPY openapi.json orval.config.ts index.html vite.config.ts build-constants.ts ./
 COPY tsconfig.json tsconfig.app.json tsconfig.node.json ./
 COPY public ./public
 COPY src ./src

src/auth/AuthContext.test.tsx

@@ -256,7 +256,7 @@ describe("AuthContext", () => {
       expect(window.location.href).toBe("/app/login");
     });
 
-    expect(api.post).toHaveBeenCalledWith("/auth/logout");
+    expect(api.post).toHaveBeenCalledWith("/auth/logout", {});
     expect(setCsrfToken).toHaveBeenLastCalledWith(null);
   });
 

src/auth/AuthContext.tsx

@@ -136,7 +136,9 @@ export function AuthProvider({ children }: { children: ReactNode }) {
 
   const logout = useCallback(async (): Promise<void> => {
     try {
-      await api.post<{ ok: boolean }>("/auth/logout");
+      // Empty body would still send Content-Type: application/json, which Fastify's
+      // default JSON parser 400s on — send {} to keep the header/body honest.
+      await api.post<{ ok: boolean }>("/auth/logout", {});
     } catch {
       // Client-side logout should still complete if the server-side session is already gone
       // or the CSRF token has expired.