[feat]: Rename `<pf-spinner>` to `<pf-v5-spinner>`

[bennypowers]

Summary

Rename <pf-spinner> to <pf-v5-spinner> and update associated CSS custom properties to use the pf-v5 prefix.

Scope

• Rename element tag from pf-spinner to pf-v5-spinner
• Rename all CSS custom properties (e.g. --pf-spinner--* to --pf-v5-spinner--*)
• Update internal class names, imports, and type declarations

Requirements

• MUST maintain feature parity with the current <pf-spinner> implementation
• MUST rename all public CSS custom properties
• MUST update HTMLElementTagNameMap declarations
• SHOULD provide a codemod or migration guide for downstream consumers