[plan] Add network shorthand documentation and canonicalize valid values for network.allowed

[github-actions]

Objective

Clarify which values are valid in network.allowed so workflow authors don't use ambiguous or invalid shorthands like npm instead of registry.npmjs.org.

Context

Discussion #22071 — Agent Persona Exploration found that network.allowed was set to npm as a shorthand for npm registry access, which may not be a valid gh-aw syntax value. Valid values should be explicit domain names.

Approach

1. In AGENTS.md, update the network configuration section to list explicitly valid and invalid values for network.allowed
2. Add a table or list of common approved domains (e.g., registry.npmjs.org, pypi.org, github.com) and clarify that bare shorthands like npm, pypi, localhost are not valid unless specifically supported
3. Check whether any shorthand aliases are actually implemented in the compiler or schema — if so, document them; if not, explicitly warn against them
4. Update the frontmatter schema or add compiler validation/warning for unrecognized shorthands
5. Update relevant skills with the same guidance

Files to Modify

• AGENTS.md — AI Engine Support / network section
• pkg/parser/schemas/ — Frontmatter schema for network.allowed (if applicable)
• skills/ — Any workflow authoring skill touching network config

Acceptance Criteria

• AGENTS.md clearly lists valid network.allowed domain examples
• Bare shorthands (e.g., npm) are explicitly marked as invalid or documented if supported
• Compiler or schema validation warns on unrecognized shorthand values (if feasible)

Generated by Plan Command for issue #discussion #22071 · ◷

• expires on Mar 23, 2026, 5:06 AM UTC

[pelikhan]

@copilot create a .github/aw/network.md file with these explanations and link it from the agentic-workflows.agent.md agent.