Add GitHub Workflows profiles and harden VS Code profile tooling

[trumpyla]

Summary

This change introduces new GitHub Workflows profiles for VS Code and implements comprehensive improvements to the profile tooling infrastructure based on the harden-vscode-profile-tooling proposal.

Key Changes

New Features

• GitHub Workflows profiles: Added github-workflows-crisp and github-workflows-retina profiles with GitHub Actions extensions (vscode-github-actions, vscode-pull-request-github, GitHub Copilot)
• OpenSpec agent documentation: Added comprehensive AGENTS.md guide for AI assistants working with OpenSpec
• Profile updates: Updated AI profile configurations (ai-plus, ai-profile) with latest settings

Improvements

• Script hardening: Enhanced reliability and portability of profile tooling scripts
• Documentation alignment: Synced README and agent docs with current behavior
• OpenSpec reorganization: Cleaned up completed changes and moved to new structure

Files Changed

New profiles:

• profiles/github-workflows-crisp/ - Crisp theme variant for GitHub workflows
• profiles/github-workflows-retina/ - Retina theme variant for GitHub workflows
• _overrides/github-workflows-base.jsonc - Base configuration for GitHub workflows profiles

OpenSpec additions:

• openspec/AGENTS.md - Comprehensive guide for AI coding assistants
• agents/openspec/changes/harden-vscode-profile-tooling/ - New change proposal with specs and tasks

Profile exports:

• exports/github-workflows-crisp.code-profile
• exports/github-workflows-retina.code-profile

Updated:

• All merged profile configurations (_merged/*.json)
• All exported profiles
• Profile management scripts
• OpenSpec project documentation

Implementation

This change follows the OpenSpec workflow defined in openspec/AGENTS.md:

1. Proposal created and validated
2. Implementation tracked via tasks.md
3. All changes aligned with spec deltas

Testing

• Validate JSON configurations: scripts/validate-json.sh
• Test profile imports: scripts/import-profile.sh
• Verify extension installations: scripts/install-extensions.sh
• Test profile opening: scripts/open-profiles.sh
• Run script tests: scripts/tests/run.sh
• Validate OpenSpec: openspec validate harden-vscode-profile-tooling --strict

Related

• OpenSpec change: harden-vscode-profile-tooling
• Specs affected: vscode-profile-tooling, performance-benchmarking