Dev: let Electron orchestrate random ports for server + Vite

[AntonNiklasson]

Problem

pnpm dev runs three things concurrently on hardcoded ports — server on 7100, Vite on 7200, Electron pointing at 7200. If a stale pnpm dev instance is still running (easy to forget across terminals/IDE windows), a new one fails with a cryptic EADDRINUSE stack.

The packaged desktop build already grabs a random port via findFreePort() in packages/desktop/src/main.ts and the frontend doesn't need to know it (Hono serves the web bundle on the same origin in packaged mode, and Vite proxies /api in dev — either way React just calls relative /api/... URLs).

Proposal

Make Electron the dev orchestrator so dev mirrors packaged:

• pnpm dev becomes pnpm --filter @github-dashboard/desktop dev (Electron is the only entry point).
• Electron main, in dev mode, picks two free ports, then spawns:
  • the server as a child with PORT=<srv>
  • Vite as a child with --port <web> and GHD_API_PORT=<srv>
• packages/web/vite.config.ts reads GHD_API_PORT for server.proxy['/api'].target.
• Electron waits for both, then loadURL("http://localhost:<web>").

Consequences

• No more port conflicts between concurrent pnpm dev instances — each gets a fresh pair.
• Dev and packaged orchestration live in one file (main.ts).
• The non-Electron browser dev workflow (point Chrome at localhost:7200) goes away. Acceptable — the primary dev surface is the desktop app.
• CLAUDE.md validation guidance needs updating (no more fixed 7100/7200 in dev).

Open questions

• Tooling like the Playwright MCP currently assumes http://localhost:7200. We'd need a stable way to discover the current dev URL — e.g. write .logs/ports.json on startup.