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/features/email-system.md

@@ -171,7 +171,7 @@ Templates use Jinja2 syntax for variable interpolation:
 Run the seed script to populate default templates:
 
 ```bash
-python scripts/seed_email_templates.py
+python scripts/seed/seed_email_templates.py
 ```
 
 This creates templates for:
@@ -302,7 +302,7 @@ Test coverage includes:
 app/services/email_service.py    # Email service with provider abstraction
 models/database/email.py         # EmailTemplate and EmailLog models
 app/core/config.py               # Email configuration settings
-scripts/seed_email_templates.py  # Template seeding script
+scripts/seed/seed_email_templates.py  # Template seeding script
 ```
 
 ### Provider Abstraction