docs: update ADR-12 and Self-Hosting for single multi-user Worker
- ADR-12: WORKER__USER is now optional; default is one Worker processing
all users in round-robin order; dedicated binding remains supported
- Self-Hosting: rewrite multi-user section to reflect single-Worker default;
show subdirectory mount pattern; dedicated Worker as an optional variant
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
docs: restructure wiki for self-hosters and contributors
- Split Architecture-Decisions into Deployment-Decisions (ADRs 1,5,6,9,11,12)
and Engineering-Decisions (ADRs 2,3,4,7,8,10)
- Add ADR-11 (exclusive NAS path ownership) and ADR-12 (WORKER__USER binding)
- Add Features page in plain language for self-hosters
- Add Self-Hosting page with quick start, multi-user setup, and config reference
- Rewrite Home as a navigation hub split by audience
- Convert Architecture-Diagrams from broken Structurizr DSL to native Mermaid
- Update Database-Architecture ERD: add RefreshToken, is_admin, display_weight
- Update Solution-Overview: remove unbuilt UI section, fix Worker description
- Delete Roadmap (duplicated GitHub Issues), Requirements (replaced by Features),
Architecture-Decisions (split into two pages), orphaned PNG images
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>