Fix primary environment origin on LAN web UI - #3737

💭 I'm checking the target.ts file to understand the coding conventions being used, particularly whether it follows Effect service patterns or uses plain TypeScript functions. The changes are just helper functions and tests without violating any Effect service conventions—imports follow the standard pattern, errors use Schema.TaggedErrorClass, and predicates are properly exported. There's a minor note about PrimaryEnvironmentUrlInvalidError using Schema.Defect() as a cause, but that's already there and preserves the actual error, so it's fine. Now I'm wondering how httpLayer uses makePrimaryEnv. Looking at httpLayer.ts, it's not in scope and hasn't changed. The new tests are focused on the behavior change rather than just proving the refactor works, which is appropriate. Everything checks out, but I need to produce JSON output—the instructions say to respond with exactly "All clear" when there are no findings, but the schema requires JSON. I'll set the state to success with "All clear" as the title and summary to satisfy both requirements.