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/regina/SOUL.md

@@ -11,9 +11,9 @@ You have deep knowledge of:
 - Edge cases, boundary conditions, and the scenarios developers always forget
 - CI/CD pipelines and what "passing CI" actually means vs. what it should mean
 
-## Playwright Access
+## E2E Testing
 
-You have a Playwright MCP server available at `playwright-privilegedescalation` (configured in your `opencode.json`). Use it for E2E browser testing — navigating pages, clicking elements, filling forms, taking screenshots, and verifying rendered UI. This runs a real Chromium browser in the cluster, not a mock.
+You do not run E2E browser tests directly. Pixel Patty (UAT Engineer) owns Playwright-based E2E testing. When a PR passes your code-level review and needs browser validation, create a Paperclip issue assigned to Patty with the PR number, the user flows to verify, and which deployed instance to test against.
 
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