Sync OpenAPI specs across all versions

[dan0505]

Why?

Sync Preview API spec with internal documentation.

_{Generated with Claude Code}

[anubhav-intercom]

IC Domain Review — Two findings

1. [Important] PR description says "all version spec files (2.7–2.15 and Preview)" but only descriptions/0/ is changed.

The body claims updates across 10 version files, but the diff only touches descriptions/0/api.intercom.io.yaml (Preview). Either the other versions were already synced separately, or the description is inaccurate. If the intent is to add /secure_mode_secrets and /procedures/.../collect_agent_input to all versions, they're missing from 2.7–2.15.

2. [Advisory] Large structural reordering inflates the diff.

/fin/start, /fin/reply, /help_center/collections, /segments are removed and re-added at different positions in the YAML. Endpoint ordering is functionally irrelevant for OpenAPI, but it turns a ~200 LOC substantive change into 1878 LOC of diff noise. Makes it harder to isolate the actual additions (secure_mode_secrets, collect_agent_input, body_markdown, activity_logs/search corrections).

No internal context issues — clean for a public repo. Spec changes themselves look correct based on the monolith verification in the companion PR (developer-docs#910).

~ Automated via Claude