build: introduce a root Makefile for unified build orchestration

[kheersagarpatel]

Summary

XenevaOS currently relies on individual component Makefiles and build scripts. As GCC support continues to expand, the project would benefit from a single root-level Makefile that orchestrates the complete build process.

Proposal

Introduce a root Makefile that:

• Builds components in dependency order:
  • Libs (XEClib, XECrt, Chitralekha)
  • KernelAA64
  • Drivers
  • Process
• Invokes the existing packaging workflow.
• Provides common targets such as:
  • all
  • clean
  • rebuild
  • component-specific targets where appropriate.

Benefits

• Simplifies the build workflow.
• Reduces manual build ordering.
• Provides a consistent entry point for GCC/Linux builds.
• Improves maintainability as additional components are ported.