docs: update all docs for optional-skills and browse command
Update 7 documentation files to reflect:
- optional-skills/ directory in all project structure trees
- 'hermes skills browse' in all CLI command listings
- '/skills browse' in all slash command references
- Three-tier skill placement (bundled → optional → hub)
- 'official' trust level in trust level tables
- Updated /skills description from 'Search, install...' to 'Browse, search...'
Files updated:
- CONTRIBUTING.md (skill classification, project tree, section title)
- AGENTS.md (project tree, Skills Hub description, source adapters list)
- website/docs/reference/cli-commands.md (CLI table, slash command table)
- website/docs/developer-guide/creating-skills.md (structure, classification, trust)
- website/docs/user-guide/features/skills.md (hub commands, trust table, slash commands)
- website/docs/user-guide/cli.md (slash command description)
- website/docs/developer-guide/architecture.md (project tree)
5ce2c47d60