Draft changelog: Sep 6 auth and streaming latency updates

[mintlify]

Summary

Adds a Sep 6, 2026 changelog entry covering product changes shipped since the Sep 1 entry.

Changes

• Documents OAuth 2.0 user-context (and OAuth 1.0a) support on webhook management endpoints and X Activity API subscription update/delete endpoints.
• Documents the streaming P99 latency improvement from ~6-7 seconds to ~4-5 seconds across v2 streaming endpoints.

Context

All merged PRs since the last entry were automated OpenAPI spec syncs; the entry reflects the user-facing spec changes (expanded auth options, updated latency figures). Internal reorderings and docs-only edits were excluded.

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Project	Status	Preview	Updated
x-corp	🟢 Ready	View Preview	Sep 6, 2026, 5:09 PM

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