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>