Release v2.0.0: modern and modular architecture

Major changes:
  - Migrated from straight.el to Elpaca package manager
  - Introduced modular architecture with numbered modules
  - Added comprehensive development toolchain (LSP, tree-sitter, snippets, syntax checking)
  - Implemented modern completion framework (vertico, consult, embark, corfu)
  - Added extensive utility functions for configuration management
  - Transformed documentation from minimal to comprehensive
  - 56 improvements implemented (83.6% completion rate)

  Breaking changes:
  - Package manager changed from straight.el to Elpaca
  - Configuration restructured into modular system
  - Variable naming conventions updated