[adamtheturtle]

Shared VWS and query clients currently use the SDKs' default service URLs. Supply base_vws_url and base_vwq_url through backend fixtures and pass them to all four shared clients, including clients for inactive projects. This lets a consuming backend provide the addresses of its running services.

This two-file follow-up to #3744 advances #3738, part of #3737. Further URL and backend decoupling remains in #3738.

Validation:

• Python 3.15: 50 database-summary, target-list, query-success, and inactive-query tests pass across the in-memory and Flask backends with synthetic credentials and retries disabled. Twenty-five real-Vuforia cases are skipped locally.
• Reused four existing API tests from a separate consumer harness that loads the shared fixtures as a plugin and overrides both service URLs. Active and inactive VWS/query clients all pass against MockVWS configured with those custom URLs. All six changed/added fixture bodies are covered across the targeted runs.
• Pre-commit and pre-push hooks pass, including CI partition validation, Mypy, Pyright, public type completeness, Ty, and Pyrefly. Pylint passes for both changed files, and git diff --check passes.

Full-suite coverage and real-Vuforia validation remain for hosted CI.