Scan codebase for user-facing references to 'azd' and ensure consistent lowercase usage

[JeffreyCA]

There are user-facing strings, error messages, and other outputs in the codebase that refer to the Azure Developer CLI as 'azd', 'AZD', 'Azd', and possibly other variations. For UX consistency, we should review the entire codebase and ensure that all user-facing references use 'azd' (lower-case only).

Task:

• Scan the codebase (including extensions) for all user-facing strings, error messages, documentation snippets, and output that reference the CLI name.
• Exclude: eng/, pipelines
• Update any occurrence of 'AZD', 'Azd', or other variants to 'azd' in all user-facing contexts.

Note:

• This does not affect internal variable names, config options, or environment variables - only user-facing output.
• When in doubt about string intent, err on the side of consistency with the branding guidelines.