fix: write language field to codeflash.toml for Java projects

configure_java_project() wrote module-root and tests-root but not
language. Downstream, process_pyproject_config() checks
config.get("language") == "java" to set is_java_project, so without
this field the pipeline couldn't identify the project as Java.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mohamedashrraf222

codeflash/cli_cmds/init_java.py

@@ -456,6 +456,7 @@ def configure_java_project(setup_info: JavaSetupInfo) -> bool:
     source_root = setup_info.module_root_override or detect_java_source_root(curdir)
     test_root = setup_info.test_root_override or detect_java_test_root(curdir)
 
+    config["language"] = "java"
     config["module-root"] = source_root
     config["tests-root"] = test_root