Add CLAUDE.md documentation for Claude Code (#1118)

* Add CLAUDE.md documentation for Claude Code

This file provides comprehensive guidance for Claude Code when working
in this repository, including:

- Critical plugin architecture and command patterns
- Operating modes (Regular vs IoP mode)
- Testing and development workflows
- UI development guidelines with TableIndexPage patterns
- Architecture overview and code organization
- Troubleshooting common issues
- Contributing and PR workflow

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* Add .claude to .gitignore

* Document Katello overrides and extensions in CLAUDE.md

Add comprehensive documentation of all Katello classes that
foreman_rh_cloud patches or extends, including:

- Host::Managed extensions (RhCloudHost concern)
- ManifestImportSuccess notification action override
- CandlepinDynflowProxyController hooks for IoP inventory reports
- OrganizationsController smart proxy auth patches
- RepositoriesController smart proxy auth patches

This helps prevent Katello regressions by making integration
points visible to developers and AI assistants.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* Add symlink for GitHub Copilot instructions

Create .github/copilot-instructions.md as a symlink to CLAUDE.md
so that GitHub Copilot can also use the same documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

---------

Co-authored-by: Claude <[email protected]>

Author: jeremylenz

.github/copilot-instructions.md

@@ -0,0 +1 @@
+../CLAUDE.md

.gitignore

@@ -18,3 +18,4 @@ Gemfile.lock
 .tags*
 .rubocop*--*
 public/
+.claude