Fix Windows path handling for canonical schema fragments in forms_test.go

### Current Behavior `go test ./validation/...` fails on Windows in `validation/forms_test.go` because canonical paths with `#/components/...` fragments are joined with `filepath.Join`, which turns the fragment into a Windows path segment like `#\components\...`. ### Expected Behavior The test should preserve the JSON Pointer fragment exactly as `#/components/...` while joining only the filesystem path portion, so validation passes on Windows the same way it does on macOS and Linux. ### Screenshots/Logs ```text --- FAIL: TestFormSchemasAreSubsetOfCanonical (0.01s) forms_test.go:113: canonical E:\Files\....\schemas\schemas\constructs\v1beta1\credential\api.yml#\components\schemas\Credential: fragment segment "\\components\\schemas\\Credential" not found ``` ### Environment - **Host OS:** Windows - **Platform:** Docker or Kubernetes - **Meshery Server Version:** stable-v - **Meshery Client Version:** stable-v <!-- Optional ### To Reproduce 1. Go to '...' 2. Click on '....' 3. Scroll down to '....' 4. See error --> --- ### Contributor [Guides](https://docs.meshery.io/project/contributing) and [Handbook](https://meshery.io/community/handbook) - 🛠 [Meshery Build & Release Strategy](https://docs.meshery.io/project/contributing/build-and-release) - 📚 [Instructions for contributing to documentation](https://github.com/meshery/meshery/blob/master/CONTRIBUTING.md#documentation-contribution-flow) - Meshery documentation [site](https://docs.meshery.io/) and [source](https://github.com/meshery/meshery/tree/master/docs) - 🎨 Wireframes and [designs for Meshery UI](https://www.figma.com/file/SMP3zxOjZztdOLtgN4dS2W/Meshery-UI) in Figma [(open invite)](https://www.figma.com/team_invite/redeem/GvB8SudhEOoq3JOvoLaoMs) - 🙋🏾🙋🏼 Questions: [Discussion Forum](http://discuss.meshery.io) and [Community Slack](https://slack.meshery.io)