feat(dev_tools): add diagnostics hub with permissions audit tool

Evolve the platform-debug page into a diagnostics hub with sidebar
explorer layout. Add permissions audit API that introspects all
registered page routes and reports auth/permission enforcement status.

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

app/modules/dev_tools/routes/api/admin.py

@@ -7,6 +7,9 @@ Aggregates all admin API routers for the dev-tools module.
 
 from fastapi import APIRouter
 
+from app.modules.dev_tools.routes.api.admin_diagnostics import (
+    router as diagnostics_router,
+)
 from app.modules.dev_tools.routes.api.admin_platform_debug import (
     router as platform_debug_router,
 )
@@ -19,3 +22,4 @@ router = APIRouter()
 router.include_router(sql_query_router, tags=["sql-query"])
 router.include_router(platform_debug_router, tags=["platform-debug"])
 router.include_router(translations_router, tags=["translations"])
+router.include_router(diagnostics_router, tags=["diagnostics"])