Webhooks: emit an event for the soft needs-reconnect state

Job story: When an account starts needing reconnection but its token is still valid, I want a webhook for that transition, so I can prompt the user right away instead of polling.

Problem: account.disconnected fires only on hard deactivation (isActive:false — token expired/revoked, or an intentional disconnect). But an account can enter a needs-reconnect state without the token being revoked — e.g. needsReconnection: true after a platform security checkpoint, with the token still valid. That transition emits no webhook, so the most common "please reconnect" case is invisible to integrations and only detectable by polling.

Frequency: The soft/checkpoint case is common in day-to-day operation — it's exactly the state end users see surfaced as "account needs reconnecting."

Current workaround: Polling /v1/accounts for needsReconnection, and reconciling that against account.disconnected for the hard case.

Desired outcome: A webhook fires when an account transitions into needsReconnection: true, and a recovered signal fires when it clears — without requiring a full OAuth reconnect. Open to alternatives (a dedicated account.needs_reconnect event, or extending an existing account event with a field).