dev: make the dev server port configurable via OC_DEV_PORT

[julianjelfs]

Small dev-tooling quality-of-life change (no product impact).

build_dev.sh hardcoded export OC_DEV_PORT=5001, and vite.config.ts hardcoded const port = 5001 — used for both the HTTP server and the HMR WebSocket. So prepending OC_DEV_PORT=5002 npm run dev was silently ignored (both the source and its HMR socket still tried 5001).

Both now read a pre-set OC_DEV_PORT and default to 5001, so the default workflow is unchanged but you can run a second dev server on another port — e.g. an OC_APP_STORE=true app-store build alongside the normal web one:

OC_APP_STORE=true OC_MOBILE_LAYOUT=v2 OC_DEV_PORT=5002 npm run dev

🤖 Generated with Claude Code

[github-actions]

canbench 🏋 (dir: .)

./canbench_results.yml is up to date ✅

---------------------------------------------------

Benchmark: add_reactions
  total:
    instructions: 1.36 B (0.01%) (change within noise threshold)
    heap_increase: 5 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: push_simple_text_messages
  total:
    instructions: 208.04 M (0.06%) (change within noise threshold)
    heap_increase: 12 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------