fix(signals-dashboard): declare @github/copilot-sdk dependency

signals-dashboard imports '@github/copilot-sdk/extension' but shipped
without a package.json — the only SDK-importing extension in the repo
missing one (every peer that imports the SDK declares it). Without the
manifest the host has no dependency to resolve at load time. Add a
package.json matching the peer shape (type: module, main: extension.mjs,
'@github/copilot-sdk': latest — the modal peer convention).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 26faf13e-639c-4a21-ac05-c0dc2bff7c62

extensions/signals-dashboard/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "signals-dashboard",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "extension.mjs",
+  "dependencies": {
+    "@github/copilot-sdk": "latest"
+  },
+  "description": "Real-time agent coordination dashboard for The Workshop. Shows desk status, signal types (done, checkpoint, blocked, hands-up, partnership), intent text, outcome pairing with honesty gap, token usage, and stash/restore controls.",
+  "keywords": [
+    "agent-signals",
+    "dashboard",
+    "multi-agent",
+    "coordination",
+    "canvas"
+  ]
+}