feat: initialize xinglian scheduler platform

[HSYicoX]

Summary

• add a FastAPI backend that models multi-architecture servers, scheduling logic, and lifecycle actions for 星联调度
• create a lightweight web console for registering servers, dispatching tasks, and triggering docker/system workflows
• document project usage, add licensing, dependencies, and pytest coverage for the core scheduler

Testing

• python -m compileall backend
• pytest (fails: missing optional dependency sqlalchemy in the execution environment)

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https://chatgpt.com/codex/tasks/task_e_68f7c2535b7083319dc0528c56914889

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Remove @contextmanager from FastAPI session dependency

get_session is decorated with @contextmanager, so Depends(get_session) injects the context-manager object rather than a SQLAlchemy Session. Any endpoint that tries to use session.add/session.commit will crash with AttributeError, and the underlying session is never entered or closed. Define the dependency as a plain generator (no decorator) or split the context manager into a separate helper so API routes receive a real session.

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