Improve GitHub Actions workflows: add job names, refine caching, and enhance Cabal matrix

[webdevred]

This PR improves CI workflows for building and testing the project across platforms and GHC versions. Key changes include:

• Improved job naming: All jobs now have clear name fields for better visibility in the Actions UI.
• Refined cache keys: Separate hashes for stack.yaml.lock and package.yaml improve cache hit accuracy.
• Unified and clarified Cabal matrix job:
• Tests with multiple GHC versions (9.4.7, 9.6.6, and latest) on Ubuntu.
• Uses --allow-newer=base with latest to catch future incompatibilities early.
• Enables the dump-ast flag to ensure internal tooling builds correctly (should we consider skipping validating this builds?)
• Includes in-code comments explaining these decisions.
• New Windows Cabal job: Adds build-with-cabal-windows, testing with the latest GHC and Cabal on Windows to future-proof the build pipeline across OSes.
• Cosmetic improvements: YAML formatting, consistent run: >-, and removal of redundant paths in cache (e.g., ~/.ghcup).

Together, these changes strengthen cross-platform support, cache efficiency, and long-term maintainability of the Haskell CI configuration.