fix: restore native browser ESM imports (#2495)

- [x] I understand that this repository is auto-generated and my pull
request may not be merged

## Changes being requested

Fixes #2494.

- Rewrite emitted ESM references to the private X.509 state package
import into browser-resolvable relative imports.
- Keep one private state registry across Node CommonJS and ESM consumers
while allowing native browsers to load the SDK directly.
- Preserve browser credential protections, blocked internal package
exports, and compatibility with browser `process`, `module`, and
`exports` shims.

This is intentionally the production-only release fix. Expanded browser
and bundler regression coverage will follow separately.

## Additional context & links

Verified locally:

- Real headless Chrome directly imports the built SDK without an import
map and rejects browser API-key usage by default, including with browser
`process`, `module`, and `exports` shims.
- Browser-targeted ES2020 bundling succeeds.
- Node 22.0.0 preserves both mixed CommonJS/ESM X.509 authentication
combinations.
- Existing packed-package checks pass, including CommonJS, ESM, browser
conditions, and optional dependencies.
- `pnpm build`, `pnpm lint`, `pnpm exec tsc`, and 196 focused
authentication/browser-security tests pass.
- The complete existing test suite previously passed: 7,548 tests, with
2 skipped.