Feature Request: Add support for .CLAUDE.md files

Summary
Add support for .CLAUDE.md files (with dot prefix) to allow hiding Claude instruction files from file-based wiki systems and documentation generators.

Problem
Currently, Claude Code instruction files (like CLAUDE.md) are visible to file-based wiki systems, documentation generators, and static site generators that automatically index .md files in repositories. This can clutter documentation sites and expose internal Claude instructions that are meant for development workflow rather than end-user documentation.

Proposed Solution
Extend Claude Code to recognize and process .CLAUDE.md files in addition to the current CLAUDE.md format.

Files with the dot prefix would:

• Be hidden from most file-based wiki systems (similar to how .gitignore, .env, etc. are hidden)
• Still be fully accessible and processable by Claude Code
• Maintain the same functionality and syntax as regular CLAUDE.md files

Use Cases

• Documentation Sites: Repositories using GitHub Pages, GitBook, or similar wiki systems that automatically scan for .md files
• Clean Repository Structure: Keeping Claude instructions separate from user-facing documentation
• Team Workflows: Allowing teams to use Claude Code without exposing internal instructions in their documentation

Additional Context
This follows the common convention of using dot-prefixed files for configuration and tool-specific files that should be hidden from general file browsers and documentation systems. Examples include .gitignore, .env, .eslintrc, etc.