Initial commit: AirCoding V1.0.0 Alpha architecture baseline

Complete architecture document set with multi-model review remediation:
- Frozen interface contracts, runtime semantics, DB schemas
- Event/tool/error/provider registries
- Scheduler and main agent state machines
- C4 module/code views, solution architecture, baseline V1
- Multi-model review reports and joint assessment
- Phase-gate remediation complete (P0/P1/P2/UX resolved)
- Implementation plan with T-000A through T-045
- Reference folders kept as placeholders only

reference/atuin-18.16.1/.gitignore

@@ -0,0 +1,17 @@
+.DS_Store
+/target
+*/target
+.env
+.idea/
+.vscode/
+result
+publish.sh
+.envrc
+.planning/
+
+ui/backend/target
+ui/backend/gen
+
+sqlite-server.db*
+
+.atuin/permissions.*.toml