fix(cmd/boot): support array patch operations for boot resources

[synackd]

Description

Generate RFC 6902 JSON Patch payloads when boot <resource> patch commands use --add or --remove so array updates can be represented correctly. Use key-value/merge-patch method for --set-/--unset updates, but switch the selected patch method automatically when array operations are present.

Allow patch payload data to be an object or array by widening boot-service patch client arguments from map[string]interface{} to interface{}. This lets RFC 6902 patch documents pass through as top-level arrays.

Update --remove semantics to remove by array index instead of by value, and document that --add appends to an existing array. Refresh the manual page patch forms to include inline -d data and align BMC, config, and node command documentation.

Add tests for:

• RFC 6902 array payload parsing
• dot-path to JSON Pointer conversion and escaping
• keyval patch data generation
• RFC 6902 patch data generation for add/remove
• invalid remove index rejection

This will likely affect #98.

Checklist

• My code follows the style guidelines of this project
• I have added/updated comments where needed
• I have added tests that prove my fix is effective or my feature works
• I have run make test (or equivalent) locally and all tests pass
• DCO Sign-off: All commits are signed off (git commit -s) with my real name and email
• REUSE Compliance:
  • Each new/modified source file has SPDX copyright and license headers
  • Any non-commentable files include a <filename>.license sidecar
  • All referenced licenses are present in the LICENSES/ directory

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

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[synackd]

This is now ready for review and has been rebased onto the latest main.