feat(framework): Add startup update checks for SuperLink, SuperNode, and SuperExec

[mohammadnaseri]

This PR introduces a shared startup-only update check for flower-superlink, flower-supernode, and flower-superexec.

[Copilot]

Pull request overview

Adds a shared “startup-only” Flower version update check and wires it into the flower-superlink, flower-supernode, and flower-superexec CLIs so users can be warned when they’re running an outdated runtime.

Changes:

• Introduces warn_if_flwr_update_available (and payload helpers/constants) in flwr.supercore.utils.
• Calls the update check during startup for SuperLink, SuperNode, and SuperExec.
• Adds unit tests validating the update-check behavior and request payload.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
framework/py/flwr/supernode/cli/flower_supernode.py	Invokes update check during SuperNode startup.
framework/py/flwr/supernode/cli/flower_supernode_test.py	Tests that SuperNode runs the update check after parsing args.
framework/py/flwr/supercore/utils.py	Implements update-check payload creation + HTTP call + opt-out env var.
framework/py/flwr/supercore/utils_test.py	Adds tests for payload composition, opt-out behavior, request parameters, and failure modes.
framework/py/flwr/supercore/cli/flower_superexec.py	Invokes update check during SuperExec startup.
framework/py/flwr/supercore/cli/flower_superexec_test.py	Tests that SuperExec runs the update check after parsing args.
framework/py/flwr/server/app.py	Invokes update check during SuperLink startup.
framework/py/flwr/server/app_test.py	Tests that SuperLink runs the update check after parsing args.

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[panh99]

LGTM!