#13902: fix: auto-recover on event gap instead of showing error

## Problem When WebSocket events arrive with a sequence gap (missed events), the UI and TUI previously showed an error message asking the user to refresh manually. This was disruptive and unnecessary. ## Solution Auto-recover by reloading chat history instead of showing an error. ### Changes - **UI (app-gateway.ts)**: Call `loadChatHistory()` instead of setting `lastError` - **TUI (tui.ts)**: Call `loadHistory()` with a brief 'resyncing...' status (2s instead of 5s) ### Before - UI: Error banner "event gap detected... refresh recommended" - TUI: Status "event gap: expected X, got Y" for 5 seconds ### After - UI: Silently reloads chat history (logs to console only for debugging) - TUI: Brief "resyncing (event gap X→Y)" status while reloading The gap is logged to console for debugging but no longer surfaces as a user-visible error. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR changes how the UI and TUI react to WebSocket sequence gaps: instead of surfacing an error prompting a manual refresh, both clients attempt to self-heal by reloading chat history (`loadChatHistory()` in the web UI and `loadHistory()` in the TUI). The web UI also logs a console info line for debugging, while the TUI shows a short-lived “resyncing…” status message during the reload. These changes plug into the existing gateway client gap callback (`onGap`) alongside the existing reconnect logic in `connectGateway()` and the TUI’s `GatewayChatClient` event loop. <h3>Confidence Score: 4/5</h3> - This PR is likely safe to merge, but there is one correctness concern around TUI state consistency during mid-stream gap recovery. - The changes are small and localized to gap handling, and the recovery path reuses existing history-loading code. The main risk is the TUI leaving in-flight run/status state intact while replacing history, which can produce inconsistent UI behavior when gaps occur during streaming. - src/tui/tui.ts <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->