chore: use npm ci --ignore-scripts in CI and scripts (#276)

Replaces various uses of `npm install` with `npm ci --ignore-scripts`.
This should both be more hermetic (it'll always use the locked versions
rather than re-resolving) and will partially mitigate some build-time
code execution risk.

There should be no breakage risk, as the current dependency footprint is
small and shouldn't include anything that uses build scripts 🙂

Signed-off-by: William Woodruff <william@astral.sh>

.github/workflows/test.yml

@@ -25,7 +25,7 @@ jobs:
         with:
           node-version: "20"
       - run: |
-          npm install
+          npm ci --ignore-scripts
       - run: |
           npm run all
       - name: Check all jobs are in all-tests-passed.needs