To address the deprecation of moduleResolution=node10 in TypeScript 6+, this
commit modernizes our configuration by moving to "bundler" resolution. This
strategy correctly enforces package exports maps.

Specific changes to support this strict resolution:

• Updated firebase to v12 and @types/pg to latest, as these newer versions
  correctly ship type exports that "bundler" resolution requires.
• Fixed the rxjs import in types/internal/rxjs.d.ts to use the standard
  'rxjs' entry point instead of reaching into rxjs/index.js.
• Enabled "skipLibCheck": true to avoid unrelated type-checking failures in
  third-party libraries (such as puppeteer-core's vendored rxjs types).