Add active polling to recursive mode

[Mygod]

This fixes poor download performance.

[Copilot]

Pull request overview

This PR adds an active polling mechanism to improve download performance when there are open streams but no data ready to send. The feature introduces a configurable cap on the polling backoff interval and implements exponential backoff to avoid excessive polling while maintaining responsiveness.

Changes:

• Added active_poll_cap_ms configuration parameter with validation (minimum value of 1)
• Implemented active polling logic with exponential backoff that triggers when streams exist but none are ready
• Fixed polls_sent counter to only increment after successful UDP send operations (necessary for accurate backoff calculation)

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
crates/slipstream-ffi/src/lib.rs	Added active_poll_cap_ms field to ClientConfig struct
crates/slipstream-client/src/runtime.rs	Implemented active polling logic with helper functions, exponential backoff, and integration into main event loop
crates/slipstream-client/src/main.rs	Added CLI argument, SIP003 option parsing, validation, and tests for active_poll_cap_ms
crates/slipstream-client/src/dns/poll.rs	Moved polls_sent counter increment to after successful UDP send for accurate tracking

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[Mygod]

@codex review

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Nice work!

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[Mygod]

Closing due to insufficient consideration of RTT.