SIR-1523 - Validate watched saves before upload

[KeinerM]

What changed

• Added per-save validation to raisely start for campaign styles and components before upload.
• On validation failure, the watcher now prints the validator error inline and skips upload for that save.
• Refactored watcher setup into a testable registration function so watcher behavior can be verified directly.
• Added tests covering invalid SCSS saves, invalid component saves, watcher persistence after failure, and successful recovery on the next valid save.

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Note

Medium Risk
Adds new preflight/per-save validation that can block deploy/start uploads and changes test runner/dependencies, which may affect developer workflows and release behavior if validators misreport or become unavailable.

Overview
Adds SCSS/component validation gates before uploading changes.

raisely start now validates campaign stylesheet saves and component saves via validateCampaignSass/validateComponent; failed validation prints the validator error and skips that upload while keeping watchers running (watcher logic extracted into testable helpers).

raisely deploy gains a default preflight validation step across configured campaigns and local components (with concurrency limiting) and a --no-validate escape hatch; deploy flow is refactored for dependency injection and improved error handling (e.g., missing components/ no longer crashes).

Switches tests from node:test to vitest, adds vitest to devDependencies, and introduces a package-lock.json.

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