Fix npm package error for Java language server

Remove non-existent @vscode/java-language-server npm package.
Java language server support is provided by Serena's built-in LSP
integration which manages Eclipse JDT LS internally. Updated
documentation to reflect this.

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Copilot

containers/serena-mcp-server/Dockerfile

@@ -43,7 +43,6 @@ RUN pip install --no-cache-dir git+https://github.com/oraios/serena.git || \
 RUN npm install -g \
     typescript \
     typescript-language-server \
-    @vscode/java-language-server \
     && rm -rf /root/.npm
 
 # Install Python language server (pyright is included in Serena dependencies)

containers/serena-mcp-server/README.md

@@ -12,7 +12,7 @@ A containerized version of the [Serena MCP Server](https://github.com/oraios/ser
 ## Supported Languages
 
 - **Python** (3.11+) - via pyright and python-lsp-server
-- **Java** (JDK 21) - via Eclipse JDT Language Server
+- **Java** (JDK 21) - via Serena's built-in LSP integration
 - **JavaScript/TypeScript** - via typescript-language-server
 - **Go** - via gopls
 
@@ -137,8 +137,9 @@ docker run --rm -i \
 
 ### Java
 - OpenJDK 21 is pre-installed (via default-jdk package)
-- Eclipse JDT Language Server available via npm
+- Java language server support provided by Serena's built-in LSP integration
 - Works with Maven and Gradle projects
+- Note: Eclipse JDT Language Server is managed by Serena internally
 
 ### JavaScript/TypeScript
 - Node.js and npm are pre-installed