refactor(P11+P12): codebase hygiene — CLAUDE.md rewrite, type safety, dead code removal

- Rewrite CLAUDE.md to match current 8-service architecture (was 11, 5 deleted)
- Remove all as-any casts in OrderDetail.tsx (9 casts → 0)
- Add cad_parsed_objects/cad_part_materials to OrderItem interface
- Rename require_admin → require_global_admin across 6 router files (22 calls)
- Remove EXPORT_GLB_PRODUCTION enum + generate_gltf_production_task (dead code)
- Remove worker-thumbnail from ALLOWED_SERVICES, replace Flamenco link
- Delete obsolete PLAN.md (1455 lines) and PLAN_REFACTOR.md (1174 lines)
- Fix digit-only USD prim names with p_ prefix

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

backend/app/api/routers/templates.py

@@ -6,7 +6,7 @@ from sqlalchemy import select
 from pydantic import BaseModel
 from app.database import get_db
 from app.models.template import Template
-from app.utils.auth import get_current_user, require_admin
+from app.utils.auth import get_current_user, require_global_admin
 from app.models.user import User
 
 router = APIRouter(prefix="/templates", tags=["templates"])
@@ -63,7 +63,7 @@ async def get_template(
 async def update_template(
     template_id: uuid.UUID,
     body: TemplateUpdate,
-    user: User = Depends(require_admin),
+    user: User = Depends(require_global_admin),
     db: AsyncSession = Depends(get_db),
 ):
     result = await db.execute(select(Template).where(Template.id == template_id))