refactor(scripts): reorganize scripts/ into seed/ and validate/ subfolders

Move 9 init/seed scripts into scripts/seed/ and 7 validation scripts
(+ validators/ subfolder) into scripts/validate/ to reduce clutter in
the root scripts/ directory. Update all references across Makefile,
CI/CD configs, pre-commit hooks, docs (~40 files), and Python imports.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/implementation/email-settings.md

@@ -296,7 +296,7 @@ Tests:
 - `alembic/versions/v0a1b2c3d4e5_add_store_email_settings.py` - Migration
 - `app/services/store_email_settings_service.py` - Service
 - `app/api/v1/store/email_settings.py` - API endpoints
-- `scripts/install.py` - Installation wizard
+- `scripts/seed/install.py` - Installation wizard
 
 ### Modified Files
 - `app/services/email_service.py` - Added platform config, store providers