Move adapter implementations into shared workspace packages

Extract claude-local and codex-local adapter code from cli/server/ui
into packages/adapters/ and packages/adapter-utils/. CLI, server, and
UI now import shared adapter logic instead of duplicating it. Removes
~1100 lines of duplicated code across packages. Register new packages
in pnpm workspace.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/adapters/claude-local/src/server/index.ts

@@ -0,0 +1,2 @@
+export { execute } from "./execute.js";
+export { parseClaudeStreamJson, describeClaudeFailure, isClaudeUnknownSessionError } from "./parse.js";