revert: remove CopilotKit frontend scaffolding

Reverts commits 9e08418 and 1533497. The frontend scaffolding is being
replaced with a different approach. AGUI protocol support (templates,
invoke, TUI) remains intact — only the CopilotKit frontend template
and associated wizard step/CLI flag are removed.

Author: aidandaly24

.prettierignore

@@ -1,3 +1,2 @@
 CHANGELOG.md
 src/assets/**/*.md
-src/assets/frontend/**

AGUI_INVOKE_REVIEW.md

@@ -449,16 +449,6 @@ exports[`Assets Directory Snapshots > File listing > should match the expected f
   "evaluators/python-lambda/execution-role-policy.json",
   "evaluators/python-lambda/lambda_function.py",
   "evaluators/python-lambda/pyproject.toml",
-  "frontend/copilotkit/.env.local.example",
-  "frontend/copilotkit/README.md",
-  "frontend/copilotkit/next.config.ts",
-  "frontend/copilotkit/package.json",
-  "frontend/copilotkit/postcss.config.mjs",
-  "frontend/copilotkit/src/app/api/copilotkit/route.ts",
-  "frontend/copilotkit/src/app/globals.css",
-  "frontend/copilotkit/src/app/layout.tsx",
-  "frontend/copilotkit/src/app/page.tsx",
-  "frontend/copilotkit/tsconfig.json",
   "mcp/python-lambda/README.md",
   "mcp/python-lambda/handler.py",
   "mcp/python-lambda/pyproject.toml",