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/proposals/plan-perms.md

@@ -590,7 +590,7 @@ ADD COLUMN is_custom BOOLEAN DEFAULT FALSE;
 
 2. **Migrations run:** `make migrate-up`
 
-3. **Architecture validation:** `python scripts/validate_architecture.py -v`
+3. **Architecture validation:** `python scripts/validate/validate_architecture.py -v`
 
 4. **Unit tests:** Test permission filtering logic
    - Platform with no config → all permissions allowed