fix(framework): Make Starlette a core dependency

[mohammadnaseri]

No description provided.

[Copilot]

Pull request overview

This PR makes Starlette a core flwr framework dependency (instead of being gated behind the removed rest extra) and updates user-facing guidance for exit code 601 accordingly.

Changes:

• Promote starlette to a required dependency and remove the rest optional extra.
• Regenerate/update uv.lock to reflect the dependency graph and extras list changes.
• Update exit-code help text and docs for [601] COMMON_MISSING_EXTRA_REST to instruct upgrading/reinstalling flwr.

Critical issues

• Removing the rest extra breaks internal e2e packages still depending on flwr[simulation,rest] (e.g., framework/e2e/e2e-bare/pyproject.toml, framework/e2e/e2e-scikit-learn/pyproject.toml). Those need to be updated (or an alias extra provided) to avoid installation/CI failures.

Simplicity/readability suggestions

• None.

Consistency concerns

• The improved 601 guidance may not be shown in some cases because at least one REST module imports requests symbols before the guarded import requests, causing import-time failure before flwr_exit(...) can run.
• Localized docs catalogs (framework/docs/locales/*/*.po) still include the old “install with rest extra” guidance and should be regenerated/updated after the English source change.

Whether the PR should be split

• No (changes are coherent around the dependency move), but follow-up commits are needed to update internal e2e dependency declarations and docs locales.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 3 comments.

File	Description
framework/uv.lock	Adds Starlette to core dependencies and removes the rest extra from metadata.
framework/pyproject.toml	Makes Starlette a core dependency and removes the rest optional-dependency group.
framework/py/flwr/supercore/exit/exit_code.py	Updates exit code 601 help text to reflect removal of the rest extra.
framework/docs/source/ref-exit-codes/601.rst	Updates docs instructions for resolving exit code 601 after the packaging change.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve the rest extra for compatibility

Adding Starlette as a required dependency makes the extra empty, but removing the rest extra from package metadata breaks workflows that still select it explicitly, such as uv sync --extra rest from a source checkout, and the repo still has app configs declaring flwr[simulation,rest] in framework/e2e/e2e-bare/pyproject.toml and framework/e2e/e2e-scikit-learn/pyproject.toml. Keeping rest = [] while making Starlette core would preserve those existing install paths without changing dependencies.

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