chore(eslint): ignore vendored third-party minified libraries

npx eslint . linted the newly vendored marked.min.js / purify.min.js,
producing ~1,500 style errors on third-party minified code. Exclude the
vendor directory and any *.min.js from linting so ESLint only scans
first-party source.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JjqBRjjqNLJuUCMibLDKKP

Author: DJ

.eslintignore

@@ -0,0 +1,3 @@
+node_modules/
+src/renderer/vendor/
+**/*.min.js