Initial commit: Project scaffolding + architecture documentation

- arc42 template fully populated in docs/architecture/README.md with Mermaid diagrams, quality goals, deployment view, cross-cutting concepts, risks and glossary
- Consolidated ADR-001 (merged all previous root ADR drafts)
- ADR-002: Module/folder structure decision and rationale
- ADR-003: Technology stack, language choices per module (TypeScript, Go, Bash/Python), Docker-first approach, and explicit implicit assumptions
- Updated root README.md with comprehensive Project Structure section and links to all ADRs
- Created .github/instructions/TODO.md with detailed tracking (architecture phase marked complete)
- Folder structure created matching ADR-002 (frontend/, backend/playout/, backend/chat/, backend/shared/, infrastructure/, scripts/, monitoring/)
- Git repository initialized with main branch

This establishes the foundation defined in the arc42 documentation and the three ADRs.

.gitignore

@@ -0,0 +1,2 @@
+# ignore agentic files
+.github/instructions/