Support external config file for explorer.fileNesting.patterns

### Problem The full config from this repo has ~70+ pattern entries. Pasting it into `settings.json` makes the file very long (100+ lines just for file nesting), and it clutters the main editor settings. Other tools (e.g. cSpell) support storing large config in a separate file (`cspell.json`, custom dictionary paths). It would be helpful if file nesting could do something similar. ### Suggested solution Add support for loading `explorer.fileNesting.patterns` from an external file, for example: 1. **Extension setting** – e.g. `fileNestingUpdater.configPath` - If set (e.g. `~/.config/file-nesting.json`), read patterns from that file instead of writing to `settings.json` - The extension would merge/apply this when updating 2. **Or: VSCode contribution** – a new setting like `explorer.fileNesting.configPath` - If set, VSCode reads the patterns from the given file (similar to `tsconfig` path) - Falls back to `settings.json` when unset ### Alternatives - Continue manual copy-paste; keep patterns in `settings.json` - Use extensions like "Split Configs" to split `settings.json` into multiple files ### Additional context - Many users only need a subset of patterns (e.g. Vue + PHP). A lighter config would still benefit from an external file. - Settings sync would be simpler if the large config lived in a separate, optional file. ### Validations - [x] Follow the [Code of Conduct](https://github.com/antfu/.github/blob/main/CODE_OF_CONDUCT.md) - [x] Read the [Contributing Guide](https://github.com/antfu/contribute) - [x] Checked that there isn't already an issue requesting the same feature