chore: clean up post-refactor — remove old package paths, gitignore .omo/

- Remove old top-level packages (now in domain/application/infrastructure):
  - ai/ (moved to infrastructure/ai/)
  - cashflow_model/ (moved to domain/)
  - cli/ (moved to infrastructure/cli/)
  - engine/ (moved to application/)
  - sync/ (moved to infrastructure/repositories/excel_repository.py)
- .gitignore: add .omo/ (opencode local state)
- AGENTS.md: already updated to MetaAgent v3.0 paths in T1
- data/model.json: SCHEMA_VERSION=1 added in T1

.gitignore

@@ -174,3 +174,9 @@ poetry.toml
 pyrightconfig.json
 
 # End of https://www.toptal.com/developers/gitignore/api/python
+
+# MetaAgent temp files
+.temp/
+
+# opencode local state
+.omo/