[Feature]: Surface trigger-level failures — alert on connection ERROR, show failed trigger runs in Issues

Problem

OAuth refresh fails → connection flips to ERROR (app-connection.handler.ts:184, status update only, no side effects). From then on, every incoming webhook fails silently:

• Trigger hook throws ConnectionExpired → no flow run created; payloads only submitted on OK (execute-webhook.ts:134)
• No issue, no alert — alerts fire only from flow-run hooks (flow-run-hooks.ts:38); no flow run = nothing fires
• Only signals: connection badge on Connections page + platform-admin trigger-health aggregates (per-piece counts, not per-flow)
• Payloads lost once queue retries exhaust

Verified on current main.

Ref: Pylon 2516

Proposed

Needs product scoping (Mo: per-flow Trigger Run log in UI, hidden by default; treating trigger failures as flow runs breaks retry — one payload maps to many runs, formats differ). Minimum viable:

1. Alert (email/notification) when a connection transitions to ERROR
2. Per-flow visibility of failed trigger runs — Issues entry or Trigger Runs list with a "connection error — reconnect" CTA

Prior art

• Customer PR (closed, not merged): https://github.com/activepieces/activepieces/pull/8726 — returned raw payload on trigger failure so a failed run gets created
• A TriggerRun entity existed and was removed (migration RemoveTriggerRunEntity, Oct 2025); recordTriggerRun now keeps only per-piece platform aggregatesactivepieces/activepieces#13994