fix: resolve ESM/CommonJS conflict in brainstorming server #774

[sarbojitrana]

Fixes #774

Resolves a runtime error in Node.js v25+ where the brainstorming server fails to start due to a module system mismatch.

Problem

The repository is configured with "type": "module" (ESM), but server.js uses CommonJS (require).

Node.js v25 enforces ESM strictly, resulting in:

ReferenceError: require is not defined in ES module scope

---

Solution

• Renamed server.js → server.cjs to explicitly use CommonJS
• Updated start-server.sh to reference the new file
• Updated test references to maintain consistency

Before the fix

After the fix

[obra]

Thanks @sarbojitrana! Clean fix — exactly the right approach. Cherry-picked your commit to the dev branch (preserving your authorship). Closing the PR since we applied it directly rather than merging.