Correct gh aw CLI glossary wording in environment reference side quest

[Copilot]

The side-quest environment reference described gh aw as supporting validate and run subcommands, which does not match the current documented CLI surface. This update aligns the workshop wording with documented gh aw usage.

• Scope

  • Updated workshop/side-quest-01-02-environment-reference.md only.

• Glossary copy alignment

  • Replaced inaccurate phrasing:
    • from: compile, validate, and run
    • to: compile

• Adjacent content consistency

  • Updated the gh-aw conceptual image alt text to remove run wording so surrounding instructional text and accessibility text stay consistent.

- You use `gh aw` to compile, validate, and run agentic workflow files.
+ You use `gh aw` to compile agentic workflow files.

• Fixes [workshop-sync] workshop/side-quest-01-02-environment-reference.md: gh aw described as supporting validate and run subcommands that are not docu [Content truncated due to length] #1836