Squashed commit of the following:

commit 0d624137c2557c6eeb87020749e4977b821c2b5c
Author: Adrien <adrien.cesaro@proton.me>
Date:   Thu Apr 9 11:55:22 2026 +0200

    backend native image setup

README.md

@@ -137,7 +137,7 @@ PictureGroup
 
 ## Stack
 
-- **Backend**: Spring Boot 4.0.5 + Spring AI 2.0.0-M4, Java 21, Maven
+- **Backend**: Spring Boot 4.0.5 + Spring AI 2.0.0-M4, Java 25, Maven
 - **Frontend**: Vue.js 3 + Vite + TypeScript + Pinia + Axios
 - **Database**: PostgreSQL 16 + pgvector extension
 - **Auth**: HTTP Basic (single shared in-memory user)
@@ -146,7 +146,7 @@ PictureGroup
 
 See [specs/001-neuro-rag-learning/quickstart.md](specs/001-neuro-rag-learning/quickstart.md) for full instructions.
 
-### Local Dev
+### Local Dev (JVM)
 
 ```bash
 # Start the database
@@ -162,6 +162,55 @@ npm install
 npm run dev
 ```
 
+### Native Image Build
+
+Produces a GraalVM native binary packaged into a minimal Docker image via Jib.
+
+**Prerequisite**: GraalVM 25 must be installed and set as `JAVA_HOME`.
+
+```bash
+# Install GraalVM 25 CE via sdkman (one-time)
+sdk install java 25-graalce
+sdk use java 25-graalce
+
+# Build native executable + Docker image (requires Docker daemon)
+cd backend
+mvn -Pnative package jib:dockerBuild -DskipTests
+```
+
+The image `ai-teacher-backend:latest` will appear in your local Docker. It starts in under 1 second and uses significantly less memory than the JVM image.
+
+### Run Native Stack (Docker Compose)
+
+```bash
+# Copy and fill in secrets
+cp .env.example .env
+# edit .env — add OPENAI_API_KEY at minimum
+
+# Start PostgreSQL + native backend
+docker compose -f docker-compose.native.yml up
+```
+
+App available at `http://localhost:8080`.
+
+### Build Pipeline (Native)
+
+```mermaid
+graph LR
+    SRC["Source Code\n(Java 25)"]
+    AOT["Spring Boot AOT\n(process-aot)"]
+    NI["GraalVM native-image\n(native-maven-plugin)"]
+    EXE["Native Executable\ntarget/ai-teacher-backend"]
+    JIB["Jib\n(jib-native-image-extension)"]
+    IMG["Docker Image\nai-teacher-backend:latest\n(distroless base)"]
+
+    SRC --> AOT
+    AOT --> NI
+    NI --> EXE
+    EXE --> JIB
+    JIB --> IMG
+```
+
 ### Environment Variables
 
 #### Backend