- Create scripts/run-tests.mjs to auto-discover test files, replacing
the 900-char inline test command in package.json (P3-1)
- Add test:only script for CI to avoid duplicate build+typecheck (P2-1)
- Preserve original SyntaxError as cause in responseJson (P2-3)
Change-Id: I51d0c8c51d3b0b648ed5ff4ea282bda070b0d457