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/getting-started/platform-homepage-quick-start.md

@@ -11,7 +11,7 @@ Quick reference for setting up and customizing the platform homepage and content
 Run the seeder script to create all default platform pages:
 
 ```bash
-python scripts/create_platform_pages.py
+python scripts/seed/create_platform_pages.py
 ```
 
 This creates:
@@ -253,7 +253,7 @@ Result in header: `About | FAQ | Contact`
 
 **Fix:** Run seeder script
 ```bash
-python scripts/create_platform_pages.py
+python scripts/seed/create_platform_pages.py
 ```
 
 ### Navigation menu is empty