Add Pixel Patty (UAT) and move Playwright MCP from Regina

Split QA and UAT responsibilities: Regina keeps code-level QA
(vitest, PR review, CI health) on claude_local/sonnet, while
new agent Pixel Patty handles E2E browser testing via Playwright
MCP on opencode_local/minimax — reducing token cost for the
browser-heavy automation work.

- Add engineering/patty/ with full agent file set
- Remove Playwright MCP references from Regina's SOUL.md
- Delete Regina's stale opencode.json (now on claude_local)
- Update roster, directory tree, and shared tools

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

engineering/patty/opencode.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "permission": "allow",
+  "experimental": {
+    "snapshots": false
+  },
+  "mcp": {
+    "playwright-privilegedescalation": {
+      "type": "remote",
+      "url": "http://playwright-privilegedescalation.paperclip.svc.cluster.local:3000/sse"
+    }
+  }
+}