Draft changelog: streaming latency and management auth updates

[mintlify]

Summary

Adds a Sep 5, 2026 changelog entry covering product changes shipped since the Sep 1 entry.

Changes

• Streaming delivery improvement: P99 latency on hydration-prioritized streams (Filtered Stream, volume streams) is now ~4-5 seconds, down from ~6-7 seconds.
• Expanded authentication on webhook and X Activity API management endpoints: OAuth 2.0 user context (and OAuth 1.0a where it was missing) is now accepted alongside app-only Bearer Token.

Context

Reviewed all commits merged to main since the last changelog entry. Remaining changes in that window were internal spec reordering and docs-only edits, which are excluded per changelog scope.

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Project	Status	Preview	Updated
x-corp	🟢 Ready	View Preview	Sep 5, 2026, 5:10 PM

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