Connect the two tools: cross-nav links and Send to Scope Lock handoff

- Add a header link on each tool pointing to the other.
- Add a Send to Scope Lock button on Workshop clusters that carry a
  candidate solution tag. Writes the item to a shared localStorage
  queue (sde_scope_handoff_v1).
- Scope Lock drains that queue on load and adds each item to the
  Scope Boundary Board as unsorted, deduping by a deterministic id so
  a repeat send never creates a duplicate.
- No backend needed: both tools already share the same browser origin.
- Verified with a jsdom test covering send, drain, reload, and
  re-send-after-reset.
- Update README and CHANGELOG.

README.md

@@ -99,6 +99,18 @@ The two tools store data in different ways.
 1. Click Export in the tool to create a durable record.
 2. Save the exported file to your computer or to a shared drive.
 
+## How the tools work together
+
+Each tool's header has a link to the other tool.
+
+The Field Problem Workshop can send a cluster to the Scope Lock Meeting Suite.
+
+1. Tag a cluster with a candidate solution, for example "Tracking MVP (pilot)".
+2. Click "Send to Scope Lock" on that cluster.
+3. Open the Scope Lock Meeting Suite. The cluster appears as a new, unsorted item on the Scope Boundary Board.
+
+The send action stores the item in the browser's local storage. Both tools must run from the same server address for this to work. Sending the same cluster twice does not create a duplicate item.
+
 ## Reset a tool
 
 Each tool has a Reset control.