T6: Decompose CLI — main.py → 9 command files, config.py → config_cmd.py

Split infrastructure/cli/:
- main.py (330 LOC) → 9 files in infrastructure/cli/commands/:
  * init.py, forecast.py, scenario.py, whatif.py, compare.py
  * import_xlsx.py, export_xlsx.py, analyze.py, info.py
- config.py (428 LOC) → commands/config_cmd.py (15 sub-commands)
- main.py → app.py (entry point: registers all commands)
- New: paths.py (MODEL_PATH, DATA_DIR)
- New: services.py (composition root + helpers: load_model, save_model,
  build_services, resolve_currency, convert_value, fmt_amount)
- cli/__init__.py (empty) удалён

Each command module: <100 LOC.
pyproject.toml: cf = infrastructure.cli.app:app
tests/test_cli.py: import обновлён на infrastructure.cli.app

CLI behavior идентично, все команды работают.
Tests: 67/67 pass.

tests/test_cli.py

@@ -1,6 +1,7 @@
 from typer.testing import CliRunner
 
-from infrastructure.cli.main import MODEL_PATH, app
+from infrastructure.cli.app import app
+from infrastructure.cli.paths import MODEL_PATH
 
 runner = CliRunner()