COS-123 Add backend Railway deploy README for fast setup

Author: pH-7

cortex_core/README.md

@@ -0,0 +1,39 @@
+# CortexOS Backend (Railway)
+
+## Quick Deploy
+
+From the repository root:
+
+```bash
+cd /path/to/CortexOSLLM
+railway login
+railway init
+railway up
+```
+
+This backend is deployed with:
+- `Dockerfile` (root)
+- `railway.toml` (root)
+
+Railway injects `PORT`; container startup already uses it:
+
+```bash
+uvicorn cortex_core.api.server:app --host 0.0.0.0 --port ${PORT:-8420}
+```
+
+## Verify After Deploy
+
+Replace `<your-railway-domain>` with your Railway URL:
+
+```bash
+curl https://<your-railway-domain>/health
+```
+
+Expected response includes:
+- `status: "ok"`
+- `timestamp`
+
+## Notes
+
+- Data is stored in container home (`~/.cortexos`) and is ephemeral unless you attach a Railway volume.
+- CORS is currently open (`allow_origins=["*"]`) in `cortex_core/api/server.py`.