The generate-starters script was flattening src/main/{java,resources} into
agent/{java,resources}, breaking Maven builds. Add a post-copy step that
moves them to agent/src/main/{java,resources} as Maven expects.
The langgraph-python starter crashes on Railway because of a directory
structure mismatch: agents were in agent/ with langgraph.json inside
agent/, causing langgraph_cli to fail resolving module paths.
Match the demo package's working layout:
- Move agents from agent/ to src/agents/ (same as demo)
- Put langgraph.json at project root (same as demo)
- Point entrypoint at root langgraph.json instead of agent/langgraph.json
- Templatize Dockerfile.python with AGENT_DIR and DOCKER_EXTRA_COPY vars
- Skip langgraph.json path rewriting when agentDir matches agentSourceDir
- Update tests to use framework agentDir instead of hardcoding "agent"
Regenerate all 17 starters.