feat: add MiniMax as first-class LLM provider

Add MiniMax AI as the 7th LLM provider, supporting chat (M2.7, M2.5,
M2.5-highspeed) and embedding (embo-01) models via OpenAI-compatible API.

Changes:
- Add MINIMAX enum to ChatModeType
- Add MinimaxServiceImpl chat provider (OpenAI-compat streaming)
- Add MinimaxEmbeddingProvider for vector embeddings
- Add SQL migration for provider and model registration
- Add 14 unit tests + 3 integration tests
- Update README/README_EN with MiniMax in provider list

ruoyi-modules/ruoyi-chat/pom.xml

@@ -146,6 +146,23 @@
             <artifactId>mysql-connector-j</artifactId>
         </dependency>
 
+        <!-- Test dependencies -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
 
 </project>