Wayfinder: large label set nudge

## Destination

A backlog-ready plan for a **nudge** that warns the user — before or during schema sync — when a database's combined unique node+edge label count is excessive, so they proceed with informed consent instead of hitting a silently degraded UI. This map produces **decisions only**; it does not build the dialog.

## Notes

- Domain: schema sync. See `docs/agents/schema.md`, `docs/agents/connectors.md`.
- Grilling tickets: invoke `/grilling` and `/domain-modeling`.
- Planning only — stop at "ready to build," no implementation carried into the map.
- **Facts already gathered** (feed the count-source ticket): all three connectors already call the Neptune Summary API (`fetchSummary`) and its payload already carries distinct-label counts (`numNodeLabels`/`numEdgeLabels`; RDF `classes`+predicates) — currently unused. Non-summary paths enumerate the full distinct label set (`g.V().groupCount().by(label)` etc.) *before* the expensive per-label attribute-sampling loop. Sync is TanStack-query driven (`useSchemaSync` → `schemaSyncQuery`). No pause-before-proceed pattern exists; a blocking gate would build on the existing `AlertDialog` primitive.

## Decisions so far

## Not yet specified

- Whether the nudge should also gate flows beyond schema sync.
- "Don't ask again" persistence scope (per-connection vs global) — may fold into the dialog design ticket.

## Out of scope

- A graceful/descriptive **error** message when sync *fails* on huge sets (the second Slack idea) — a separate concern that overlaps the scaling work in #2076/#2077. Not part of this nudge map.

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> [!IMPORTANT]
> Internal only — this issue is maintained by the core team and is not accepting external contributions.

Read `docs/agents/schema.md` and `docs/agents/connectors.md`, then review the gathered facts about `fetchSummary`, label enumeration, and the `useSchemaSync` → `schemaSyncQuery` flow. The issue asks for planning decisions only, including whether the nudge extends beyond schema sync and the persistence scope; stop at “ready to build.”

Written by the indexing model from the issue text.