Persistent test-context widget for the Qt client, seeded at launch

With 8 worktree environments each spawning their own Qt client instances (compass client start --colour <c> --instance-name <name>) for manual UI testing, it's easy to lose track of which running client is testing which feature/scenario. Add a new CLI flag (e.g. --test-context <path.json>, wired alongside --instance-name=/ =--instance-color in projects/ores.qt/application/src/CommandLineParser.cpp) that points at a JSON file describing what this instance is for. On launch, the client parses it and shows a small, floating, always-on-top widget (not modal — must stay visible and interactive while the user clicks through other app windows) rendering either free text or a tickable checklist, depending on the JSON shape — e.g. \{"text": "..."\} vs \{"checklist": ["step 1", "step 2", ...]\}. Checked items could persist back to the file so progress survives a client restart.

Manual QA across many parallel environments currently has no in-app memory of "what am I testing right now, and what's left to verify" — that state lives only in the tester's head or a separate scratch note, disconnected from the actual running instance. A seeded, persistent widget makes the test plan travel with the client instance itself.

• projects/ores.qt/application/src/CommandLineParser.cpp — existing --instance-name=/–instance-color= options; natural place to add --test-context.
• compass client start --colour <c> --instance-name <name> — current launch command this would extend.