refactor(manifest): improve asset tracking and manifest generation (#326)

- Extracted asset tracking logic into dedicated cssModuleHelpers utility
- Added comprehensive tests for new helper functions
- Improved manifest generation with better CSS asset handling
- Added type safety and documentation throughout
- Optimized module processing with early exit conditions

Author: pcfreak30

package.json

@@ -62,6 +62,7 @@
     "prettier": "3.3.3",
     "pretty-quick": "^4.0.0",
     "rimraf": "^6.0.1",
+    "rollup": "^4.47.1",
     "vite": "^5.4.3",
     "vitest": "^2.1.1",
     "wait-on": "^8.0.1"