fix: use manual volume at /data for Deno cache

Simplified Docker configuration to use manually mounted volume at /data
instead of complex pre-caching strategy. This approach:

- Uses ENV DENO_DIR=/data to point to manually created Railway volume
- Keeps Dockerfile simple and maintainable
- Adds --allow-read/--allow-write permissions for cache access
- Removes railway.toml volume configuration (manual setup instead)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/railway-executor/Dockerfile

@@ -4,11 +4,15 @@ FROM denoland/deno:1.39.0
 # Set working directory
 WORKDIR /app
 
-# Copy the server file
+# Set Deno cache directory to use mounted volume
+ENV DENO_DIR=/data
+
+# Copy files
 COPY server.ts .
+COPY deno.json .
 
 # Expose port (Railway will set PORT env var)
 EXPOSE 3002
 
 # Run the Deno server
-CMD ["deno", "run", "--allow-net", "--allow-env", "server.ts"]
+CMD ["deno", "run", "--allow-net", "--allow-env", "--allow-read", "--allow-write", "server.ts"]