ci(foxglove): unbreak npm ci by pinning eslint ^9.27 + legacy-peer-deps

@foxglove/eslint-plugin@2.1.0 peer-depends on eslint ^9.27, but
package.json had eslint 10.0.2, so npm ci in the release workflow
hit ERESOLVE and failed before building the Foxglove extension.

- package.json: eslint 10.0.2 → ^9.27.0 (satisfies the plugin's peer).
- package-lock.json: regenerated (resolves eslint@9.39.4).
- .npmrc (new): legacy-peer-deps=true. Needed because the lockfile's
  existing react@19 + react-dom@18 mismatch would also block npm ci;
  matches the resolution mode the original lockfile was produced under.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: facontidavide

cloudini_foxglove/.npmrc

@@ -0,0 +1 @@
+legacy-peer-deps=true