bug(backend): api/validation_dashboard imports scripts.validation_dashboard_generator from the repository root, where it is not — the generator is always a MissingDep #18291

autobot-backend/api/validation_dashboard.py appends the repository root to sys.path and does from scripts.validation_dashboard_generator import ValidationDashboardGenerator inside try/except ImportError. The generator lives at autobot-infrastructure/shared/scripts/validation_dashboard_generator.py; repository-root scripts/ has no such module. Read from code, the import fails and ValidationDashboardGenerator is always the MissingDep stand-in, so the routes that need it can only report it unavailable. Not run against a live system.

Coupled to #18288: the generator is now a recorded backend tool (it bootstraps the backend onto its own path), so the decision here is where the backend reaches it from — import it from its real location, or move the generator to the backend as a module the infra script calls — not a copy.

Acceptance criteria

• The route resolves the real generator in a checkout and an install, with a test that fails on a MissingDep.
• One definition of the generator remains.

Found while doing #18288.