fix(backend): restore full pytest suite

[alexandervazquez98]

Pre-flight Checks

• I searched existing issues for backend full-suite pytest failures and found no duplicate.
• I understand this issue needs status:approved before a PR is opened.

Bug Description

The backend full pytest suite is currently red in the Docker-based local test environment. This was discovered while verifying the category-technology-icons SDD change. Focused category-icons backend tests pass, but the full suite has many unrelated failures that block full verification gates.

Steps to Reproduce

1. Create/use a local mock .env based on .env.example with non-secret test values.
2. Start the backend test stack: docker compose up -d neo4j postgres backend.
3. Inside the backend container, install dev test dependencies if needed: python -m pip install -r requirements-dev.txt.
4. Run full backend tests: docker compose exec -T backend python -m pytest.

Expected Behavior

The backend full pytest suite should pass, or failures should be intentionally quarantined with clear ownership.

Actual Behavior

Full backend pytest result:

101 failed, 947 passed, 1 skipped

Triage summary by module:

test_cli_worker.py: 34 failures
test_routers_events.py: 13 failures
test_rtus_router.py: 12 failures
test_routers_metrics_events.py: 10 failures
test_dictionary_service.py: 8 failures
test_rtu_sensor_repo.py: 5 failures
test_event_correlation.py: 4 failures
test_routers_links.py: 4 failures
Other auth/docs/dictionary/RTU files: 11 failures
test_routers_nodes.py: 1 uncertain auth-policy failure

Focused category-icons backend verification passed separately:

docker compose exec -T backend python -m pytest tests/test_routers_catalog.py tests/test_node_service.py tests/test_topology_repo_nodes.py
117 passed

Operating System

Linux

Agent / Client

OpenCode

Shell

bash

Relevant Logs

See the triage summary above. The failure groups appear predominantly outside the category-icons change scope, but they still block full backend verification.

Additional Context

This should be handled as a separate backend test-suite stabilization issue rather than mixed into the category icon PR slice, to preserve review focus.