# Human Description
Low on time, so this one is short.
- consolidate source file and partial loader logic into `loader` module. I have more plans for this.
- ~LSP no longer uses `VALID_EXTENSIONS`, so now `.d.ts` files (and the like) will be linted as well~ LSP does not respect `.gitignore` files, so this change was reverted.
# AI Description
## Refactor Loader and Partial Loader
This PR refactors the loader and partial loader functionality in the oxc_linter crate:
* Introduce a new `Loader` struct with methods for checking if a file can be loaded and loading file contents
* Move `partial_loader` module to `loader/partial_loader`
* Rename `JavaScriptSource` to `source.rs` and move it to the `loader` module
* Update `JavaScriptSource` to use `u32` for `start` offset instead of `usize`
* Refactor `IsolatedLintHandler` to use the new `Loader`
* Update imports and module references throughout the codebase
This change improves the organization of the loader-related code and provides a more unified interface for loading different file types.
