docs: update configuration and advanced topics for Turbopack default

Phase 3: Configuration & Advanced Updates
- Update Turbopack config docs to reflect dev default behavior
- Update Memory Usage docs to mention --webpack flag requirements
- Clarify when Webpack-specific features apply
- Update condition matching documentation for new defaults

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: lukesandberg

docs/01-app/03-api-reference/05-config/01-next-config-js/turbopack.mdx

@@ -186,8 +186,8 @@ In addition, a number of built-in conditions are supported:
 
 - `browser`: Matches code that will execute on the client. Server code can be matched using `{not: 'browser'}`.
 - `foreign`: Matches code in `node_modules`, as well as some Next.js internals. Usually you'll want to restrict loaders to `{not: 'foreign'}`. This can improve performance by reducing the number of files the loader is invoked on.
-- `development`: Matches when using `next dev --turbopack`.
-- `production`: Matches when using `next build --turbopack`.
+- `development`: Matches when using `next dev`
+- `production`: Matches when using `next build`.
 - `node`: Matches code that will run on the default Node.js runtime.
 - `edge-light`: Matches code that will run on the [Edge runtime](/docs/app/api-reference/edge).