# Task: Build a Language-Dispatching Router for a New Endpoint

## Context

You are adding a new `code_review` endpoint to the codeflash-internal aiservice backend. The existing optimization and testgen endpoints both follow the same pattern: a Django-Ninja router that dispatches to language-specific handlers based on a `data.language` field. Imports are kept lazy (inside the function body) to avoid circular dependencies.

The endpoint should be registered at `/ai/code_review` and follow the same conventions as the existing 12 endpoints in `aiservice/urls.py`.

## Task

1. Write a Django-Ninja router module `code_review_router.py` that:
   - Creates a `NinjaAPI` instance named `code_review_api`
   - Has a single `POST /` endpoint that is `async def`
   - Accepts an `AuthenticatedRequest` and a request body schema
   - Dispatches by `data.language`:
     - `"javascript"` or `"typescript"` calls a JS/TS handler
     - `"java"` calls a Java handler
     - Default (Python) calls a Python handler
   - Uses lazy imports inside the function body
   - Returns typed response schemas: `response={200: SuccessSchema, 400: ErrorSchema, 500: ErrorSchema}`

2. Write a request schema `CodeReviewSchema` (inheriting from `ninja.Schema`) that includes:
   - `source_code: str`
   - `trace_id: str`
   - `language: str` with a default of `"python"`
   - `review_depth: str` with a default of `"standard"`

3. Show how this endpoint would be registered in `aiservice/urls.py` alongside the existing endpoints.

## Expected Outputs

- A `code_review_router.py` module following the codeflash conventions
- A `CodeReviewSchema` class
- A URL registration snippet
