Docs: Convert code `# NOTE:` comments to formal documentation or TODOs

[kuznero]

Description

The codebase contains numerous # NOTE: comments (e.g., in nixpkgs/opencode/default.nix and home/nixvim/default.nix) that serve as informal warnings or pending tasks. This approach lacks visibility and makes it easy for important information or tasks to be overlooked.

Implementation Requirements

1. Audit Codebase: Search for all occurrences of # NOTE: using grep or similar tools.
2. Categorize Findings:
   • Informational Notes: If the note provides important context or warnings, move it to a formal README.md or add a more descriptive, standardized comment (e.g., # WARNING:).
   • Pending Tasks: If the note describes a task to be performed, convert it to a # TODO: comment.
3. Standardize: Ensure all new comments follow a consistent format.

Definition of Done (DoD)

• All # NOTE: comments have been processed.
• Informational notes are integrated into relevant documentation.
• Pending tasks are clearly marked as # TODO:.
• The codebase is cleaner and more professional.