Align Regina with other QA agents: Playwright, generic heartbeat, dedupe policies

- Added Playwright MCP to opencode.json and SOUL.md
- Heartbeat: "Check for assigned work from Nancy" → generic inbox check
- Heartbeat: simplified PR review, CI health, and bug triage steps
- Heartbeat: removed hardcoded agent IDs from issue assignments
- SOUL.md: removed ArtifactHub rule (already in shared POLICIES.md)
- SOUL.md: updated merge language to match PR workflow policy
- TOOLS.md: added MCP Servers section

Co-Authored-By: Paperclip <noreply@paperclip.ing>

engineering/regina/opencode.json

@@ -3,5 +3,11 @@
   "permission": "allow",
   "experimental": {
     "snapshots": false
+  },
+  "mcp": {
+    "playwright-privilegedescalation": {
+      "type": "remote",
+      "url": "http://playwright-privilegedescalation.paperclip.svc.cluster.local:3000/sse"
+    }
   }
 }