A dependency the README does not justify fails the gate: “less is better” gets its enforcer #8740

docs/PRINCIPLES.md (82bd2cb6, #7641) says "no new dependency without a reason", enforced by "nothing yet". package.json now carries six devDependencies and no dependencies.

Done looks like:

• [x] README.md has one Dependencies section that names each package in package.json (dependencies and devDependencies) with one line of why.
• [x] A test reads package.json and the README and fails, naming the package, when one is not justified there. Adding a package with no line turns the gate red.
• [x] The principle's line in docs/PRINCIPLES.md names that test as its enforcer, and the principles length test still passes.

Files: README.md, docs/PRINCIPLES.md, test/dependencies-named.test.ts (new) Risks: none at runtime. Keep the test pure file reads, under 50 ms.

Reviewed pull #8756 at its head: ticked README.md has one Dependencies section that names each package in package.json (dependencies and devDependencies) with one line of why.; A test reads package.json and the README and fails, naming the package, when one is not justified there. Adding a package with no line turns the gate red.; The principle's line in docs/PRINCIPLES.md names that test as its enforcer, and the principles length test still passes..