Recognize untagged Ollama registry models in connection tests. The previous check mistook a registry port for a tag and skipped the default latest match. Add red-to-green QtTests covering exact tags and differing ports.

Documentation: update usage, AI Insights contract evidence and Unreleased. TODO is unaffected because this fixes widget-owned AI Insights, not CLI parity. make check JOBS=8 passed with 117 QML cases and one Python test skipped for missing optional KDE modules.