refactor(codemode): namespace public types

[rekram1-node]

Summary

• port merged naming audit refactor(codemode): namespace public types #35425 to v2
• group CodeMode and Tool types under their existing namespaces
• expose same-name schemas and types for CodeMode.Input, Result, Success, Failure, Diagnostic, and DiagnosticKind
• update V2 Core Execute to use CodeMode.Result, CodeMode.DataValue, CodeMode.ToolCallHooks, and Tool.Definition

The cherry-pick conflict was limited to the deleted V1 packages/opencode adapter; this port preserves that deletion.

Testing

• bun test in packages/codemode (254 passed)
• bun typecheck in packages/codemode
• bun test --only-failures in packages/core (1,150 passed)
• Prettier check for changed files
• git diff --check

Core typecheck still reports existing unrelated V2 plugin/client-generation errors; no errors originate from the changed Execute adapter.