feat(framework): Support port 0 for OS-assigned random unused port

[panh99]

Summary

• expose bound_address from generic_create_grpc_server
• use the bound address in server startup logs when ports are assigned dynamically
• update integration tests to bind on port 0 and connect via the bound address

[Copilot]

Pull request overview

This PR improves gRPC server startup logging and test robustness by exposing and using the actual bound address (especially when binding to port 0 for dynamic port allocation) across SuperLink/SuperNode components.

Changes:

• Expose the bound address from generic_create_grpc_server via server.bound_address and use it in startup logs.
• Allow port 0 in address parsing and skip port-availability checks for port 0.
• Update integration tests to bind on port 0 and (where applicable) connect using the bound address.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
framework/py/flwr/common/grpc.py	Captures the actual bound port from gRPC and exposes it as server.bound_address.
framework/py/flwr/supercore/address.py	Allows port 0 in parsing and treats it as “no need to check availability”.
framework/py/flwr/supercore/address_test.py	Updates address parsing tests to treat port 0 as valid.
framework/py/flwr/server/app.py	Logs Fleet API startup using the server’s bound address.
framework/py/flwr/superlink/servicer/control/control_grpc.py	Logs Control API startup using the server’s bound address.
framework/py/flwr/server/superlink/serverappio/serverappio_grpc.py	Logs ServerAppIo API startup using the server’s bound address.
framework/py/flwr/server/superlink/simulation/simulationio_grpc.py	Logs SimulationIo API startup using the server’s bound address.
framework/py/flwr/supercore/grpc_health/health_server.py	Logs health server startup using the server’s bound address.
framework/py/flwr/supernode/start_client_internal.py	Logs ClientAppIo API startup using the server’s bound address.
framework/py/flwr/server/superlink/fleet/grpc_bidi/grpc_server_test.py	Uses port 0 for binding in integration tests (removes “unused port” helper).
framework/py/flwr/compat/client/grpc_client/connection_test.py	Uses port 0 for server binding and connects via the server’s bound address.

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