feat(framework): Add runtime dependency installation option

[psfoley]

No description provided.

[Copilot]

Pull request overview

Adds an opt-in mechanism for installing application dependencies at runtime (via uv sync) and threads the corresponding CLI/config options through SuperNode/SuperExec and the various flwr-* app processes.

Changes:

• Introduces --allow-runtime-dependency-installation and propagates it through SuperLink/SuperNode/SuperExec process launching.
• Adds a new dependency_installer utility to create/activate a per-run/per-launch runtime environment and install dependencies via uv.
• Updates ClientApp/ServerApp/Simulation processes to optionally install dependencies and clean up the runtime environment on exit.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
framework/py/flwr/supernode/start_client_internal.py	Forwards runtime dependency install flags to the flower-superexec subprocess.
framework/py/flwr/supernode/runtime/run_clientapp.py	Optionally installs app dependencies before loading/running the ClientApp and cleans up on exit.
framework/py/flwr/supernode/cli/flwr_clientapp.py	Passes new runtime dependency install parameters into run_clientapp/superexec wrapper.
framework/py/flwr/supernode/cli/flower_supernode.py	Adds parsing/forwarding of runtime dependency installation CLI args for SuperNode.
framework/py/flwr/supercore/superexec/run_superexec.py	Plumbs index_url/runtime_dependency_install into plugin construction and deprecation log output.
framework/py/flwr/supercore/superexec/plugin/exec_plugin.py	Extends ExecPlugin to store index_url and runtime install toggle.
framework/py/flwr/supercore/superexec/plugin/base_exec_plugin.py	Adds forwarding of runtime install flags when launching app subprocesses.
framework/py/flwr/supercore/superexec/dependency_installer.py	New module implementing uv installation, dependency sync, env activation, and cleanup.
framework/py/flwr/supercore/cli/flower_superexec.py	Adds runtime dependency installation CLI args to flower-superexec.
framework/py/flwr/simulation/app.py	Optionally installs simulation app dependencies and cleans up runtime env on exit.
framework/py/flwr/server/serverapp/app.py	Optionally installs server app dependencies and cleans up runtime env on exit.
framework/py/flwr/server/app.py	Forwards runtime dependency install flags when spawning flower-superexec in subprocess isolation mode.
framework/py/flwr/common/constant.py	Adds RUNTIME_DEPENDENCY_INSTALL default toggle constant.
framework/py/flwr/common/args.py	Introduces shared CLI arg helper add_args_runtime_dependency_install and includes it in common app args.
framework/py/flwr/cli/log.py	Changes log streaming loop behavior (notably error handling wrapper removal).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.