Include source files in your Node.js bundles

### Problem Statement

At the moment, some of the stack traces are linking to source files, e.g.

```
… es/.pnpm/@sentry+node@9.40.0/node_modules/@sentry/node/src/integrations/tracing/fastify/index.ts in handleFastifyError.handleFastifyError at line 87:5
… es/.pnpm/@sentry+node@9.40.0/node_modules/@sentry/node/src/integrations/tracing/fastify/index.ts in at line 123:24
node:diagnostics_channel in Channel.publish at line 150:9
```

but these is only `build` directory in `node_modules`, making it impossible to look up the original site of the error.

### Solution Brainstorm

Related to https://github.com/getsentry/sentry-javascript/issues/17119#issuecomment-3101440061