fix: add .npmrc with strict-dep-builds=false (#366)

pnpm 10.7+ treats ignored postinstall scripts as hard errors by default,
so every plugin's release CI now fails on transitive deps like
unrs-resolver@1.11.1 (pulled in via eslint-config-etherpad). Set
strict-dep-builds=false so unknown postinstalls emit a warning instead
of failing the install.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

.npmrc

@@ -0,0 +1 @@
+strict-dep-builds=false