Adds the Architecture Decision Records that were written during the
Forgejo deployment (M7.1) as part of moving docs from the iCloud folder
into this versioned repository.
Includes:
- ADR-0001: Forgejo vs Gitea (non-profit stewardship)
- ADR-0002: ai-apps placement (no separate VM)
- ADR-0003: Native OIDC, not ForwardAuth
- ADR-0004: Subdomain code.sdda.eu
- ADR-0005: Volume mount on /data (lesson learned)
- ADR-0006: Silent SSO via OAuth2 launch URL (lesson learned)
Plus a docs/adr/README.md that explains the ADR format, lists the
current ADRs, and provides a template for future entries.
Refs OP#1118
