feat: turbostarter boilerplate

Production-ready Next.js boilerplate with:
- Runtime env validation (fail-fast on missing vars)
- Feature-gated config (S3, Stripe, email, OAuth)
- Docker + Coolify deployment pipeline
- PostgreSQL + pgvector, MinIO S3, Better Auth
- TypeScript strict mode (no ignoreBuildErrors)
- i18n (en/es), AI modules, billing, monitoring

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.context/turbostarter-framework-context/sections/web/api/mutations.md

@@ -0,0 +1,131 @@
+---
+title: Mutations
+description: Learn how to mutate data on the server.
+url: /docs/web/api/mutations
+---
+
+# Mutations
+
+As we saw in [adding new endpoint](/docs/web/api/new-endpoint#maybe-mutation), mutations allow us to modify data on the server, like creating, updating, or deleting resources. They can be defined similarly to queries using our API client.
+
+Just like queries, mutations can be executed either server-side or client-side depending on your needs. Let's explore both approaches.
+
+## Server actions
+
+Next.js provides [server actions](https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions-and-mutations) as a powerful way to handle mutations directly on the server. They're particularly well-suited for form submissions and other data modifications.
+
+Using our `api` client with server actions is straightforward - you simply call the API function on the server.
+
+Here's an example of how you can define an action to create a new post:
+
+<Tabs items={["With helper", "Without helper"]}>
+  <Tab value="With helper">
+    ```tsx
+    // [!code word:handle]
+    "use server";
+
+    import { revalidatePath } from "next/cache";
+
+    import { handle } from "@turbostarter/api/utils";
+
+    import { api } from "~/lib/api/server";
+
+    export async function createPost(post: PostInput) {
+      try {
+        await handle(api.posts.$post)(post);
+      } catch (error) {
+        onError(error);
+      }
+
+      revalidatePath("/posts");
+    }
+    ```
+  </Tab>
+
+  <Tab value="Without helper">
+    ```tsx
+    "use server";
+
+    import { revalidatePath } from "next/cache";
+
+    import { api } from "~/lib/api/server";
+
+    export async function createPost(post: PostInput) {
+      const response = await api.posts.$post(post);
+
+      if (!response.ok) {
+        return { error: "Failed to create post" };
+      }
+
+      revalidatePath("/posts");
+    }
+    ```
+  </Tab>
+</Tabs>
+
+In the above example we're also using `revalidatePath` to revalidate the path `/posts` to fetch the updated list of posts.
+
+<Cards>
+  <Card title="Server actions and mutation" description="nextjs.org" href="https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions-and-mutations" />
+
+  <Card title="revalidatePath" description="nextjs.org" href="https://nextjs.org/docs/app/api-reference/functions/revalidatePath" />
+</Cards>
+
+## useMutation hook
+
+On the other hand, if you want to perform a mutation on the client-side, you can use the `useMutation` hook that comes straight from the integration with [React Query](https://tanstack.com/query).
+
+<Tabs items={["With helper", "Without helper"]}>
+  <Tab value="With helper">
+    ```tsx
+    // [!code word:handle]
+    import { handle } from "@turbostarter/api/utils";
+
+    import { api } from "~/lib/api/react";
+
+    export function CreatePost() {
+      const queryClient = useQueryClient();
+      const { mutate } = useMutation({
+        mutationFn: handle(api.posts.$post),
+        onSuccess: () => {
+          toast.success("Post created successfully!");
+          queryClient.invalidateQueries({ queryKey: ["posts"] });
+        },
+      });
+
+      return <form onSubmit={...} />;
+    }
+    ```
+  </Tab>
+
+  <Tab value="Without helper">
+    ```tsx
+    import { api } from "~/lib/api/react";
+
+    export function CreatePost() {
+      const queryClient = useQueryClient();
+      const { mutate } = useMutation({
+        mutationFn: async (post: PostInput) => {
+          const response = await api.posts.$post(post);
+
+          if (!response.ok) {
+            throw new Error("Failed to create post!");
+          }
+        },
+        onSuccess: () => {
+          toast.success("Post created successfully!");
+          queryClient.invalidateQueries({ queryKey: ["posts"] });
+        },
+      });
+
+      return <form onSubmit={...} />;
+    }
+    ```
+  </Tab>
+</Tabs>
+
+<Cards>
+  <Card title="useMutation hook" description="tanstack.com" href="https://tanstack.com/query/latest/docs/framework/react/reference/useMutation" />
+
+  <Card title="Query invalidation" description="tanstack.com" href="https://tanstack.com/query/latest/docs/framework/react/guides/query-invalidation" />
+</Cards>