Add dns:install action to install CoreDNS

[Copilot]

This PR implements a new action to install CoreDNS with the signature dns:install as requested.

Changes

Added a new dns action package that provides automated CoreDNS installation across multiple platforms:

• Linux: Uses apt-get or yum package managers
• macOS: Uses Homebrew
• Windows: Uses Chocolatey

Implementation Details

The action follows the established PV CLI action pattern:

1. Auto-registration: Uses init() function to register the action with the dns:install signature
2. Smart detection: Checks if CoreDNS is already installed before attempting installation
3. Platform-aware: Automatically detects the operating system and uses the appropriate package manager
4. Error handling: Provides descriptive error messages if package managers are not available
5. Logging: Includes informative progress messages throughout the installation process

Usage

The action appears in the TUI menu as dns:install and can be selected to install CoreDNS on the local system.

Testing

• ✅ Unit test added to verify action registration
• ✅ All existing tests pass
• ✅ Code formatted with go fmt
• ✅ Static analysis passes with go vet
• ✅ Project builds successfully

Reference

Implementation follows the CoreDNS manual guidelines: https://coredns.io/manual/toc/

Original prompt

Create an action to install coredns. just install dont do no setup. it should have a "dns:install" signature/name

refer to this page https://coredns.io/manual/toc/

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