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/platform-homepage.md

@@ -193,7 +193,7 @@ Manage all platform content pages from a single interface:
 
 ```bash
 # Create all default platform pages
-python scripts/create_platform_pages.py
+python scripts/seed/create_platform_pages.py
 ```
 
 This creates:
@@ -568,7 +568,7 @@ return templates.TemplateResponse(
 **Solutions:**
 1. Run seeder script:
    ```bash
-   python scripts/create_platform_pages.py
+   python scripts/seed/create_platform_pages.py
    ```
 
 2. Verify page exists: