feat: add spring boot starter

Author: mekkiamiri

contrib/adk-spring-boot-starter/.gitignore

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+HELP.md
+target/
+.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

contrib/adk-spring-boot-starter/.mvn/wrapper/maven-wrapper.properties

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+wrapperVersion=3.3.4
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.11/apache-maven-3.9.11-bin.zip

contrib/adk-spring-boot-starter/README.md

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+# ADK Spring Boot Starter
+
+This starter integrates the Google Agent Development Kit (ADK) into Spring Boot applications. It provides auto-configuration for Agents, Runners, and core services like Artifacts, Session, and Memory management.
+
+## Installation
+
+Add the following dependency to your `pom.xml`:
+
+```xml
+<dependency>
+    <groupId>com.google.adk</groupId>
+    <artifactId>adk-spring-boot-starter</artifactId>
+    <version>${adk-starter.version}</version>
+</dependency>
+```
+
+## Configuration
+
+By default, the starter configures all services to use **In-Memory** implementations. This is great for local development and testing.
+
+You can configure the behavior using `application.yaml`:
+
+### 1. Artifacts Service
+
+*   **Default**: `InMemoryArtifactService`
+*   **Production**: `GcsArtifactService` (Google Cloud Storage)
+
+To enable GCS:
+
+```yaml
+adk:
+  artifacts:
+    gcs-enabled: true
+    bucket-name: "my-agent-artifacts-bucket"
+```
+
+### 2. Session Service
+
+*   **Default**: `InMemorySessionService`
+*   **Production**: `VertexAiSessionService`
+
+To enable Vertex AI Sessions:
+
+```yaml
+adk:
+  session:
+    type: VERTEX_AI
+    project-id: "my-gcp-project"
+    location: "us-central1"
+```
+
+### 3. Memory Service
+
+*   **Default**: `InMemoryMemoryService`
+
+Currently, only In-Memory memory service is supported by default.
+
+
+### 4. Run Configuration
+
+*   **Default Streaming Mode**: `NONE`
+
+To enable streaming (e.g., SSE or BIDI):
+
+```yaml
+adk:
+  run-config:
+    streaming-mode: SSE # Options: NONE, SSE, BIDI
+```
+
+*Note: Other `RunConfig` options (like modalities, audio config) will be added in future versions.*
+
+## Architecture
+
+The starter follows the Single Responsibility Principle by splitting configuration into:
+*   `AdkArtifactsAutoConfiguration`
+*   `AdkSessionAutoConfiguration`
+*   `AdkMemoryAutoConfiguration`
+*   `AdkRunConfigAutoConfiguration`
+
+Each has its own properties class (e.g., `AdkArtifactProperties`).
+
+## Usage
+
+Simply inject the beans into your application:
+
+```java
+@Service
+public class MyAgentService {
+
+    private final Runner runner;
+    // Agent bean is no longer auto-configured by default.
+    // You must define your own Agent bean or use the Runner directly.
+
+    public MyAgentService(Runner runner) {
+        this.runner = runner;
+    }
+
+    // ... use runner
+}
+```