Let ThrottledStream be a wrapper around WeightedStream

[AhmedSoliman]

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• -> Let ThrottledStream be a wrapper around WeightedStream #7
• WeightedStream parity and accssors for pinned stream #6

[Copilot]

Pull Request Overview

This PR refactors the ThrottledStream implementation to be a thin wrapper around the existing WeightedStream, eliminating code duplication and improving maintainability. The refactor standardizes the API by making the token bucket optional in both stream types.

• ThrottledStream is now a wrapper around WeightedStream with a unit weight function
• WeightedStream now accepts optional token buckets like ThrottledStream
• Version bump from 0.0.1-alpha.6 to 0.0.1-alpha.7

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/futures/stream.rs	Refactored ThrottledStream to wrap WeightedStream, made token bucket optional in WeightedStream, added PhantomPinned marker
examples/streams.rs	Increased number of concurrent streams from 100 to 1000 for testing
Cargo.toml	Version bump to 0.0.1-alpha.7

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