Function detectRuntime

detectRuntime(): RuntimeInfo
Detect the current runtime environment.

Detection order (first match wins):
1. Bun - checks for Bun global
2. Deno - checks for Deno global
3. Browser - checks for window and browser-specific APIs
4. Node.js - checks for process.versions.node
5. Unknown - fallback
Returns RuntimeInfo
RuntimeInfo with detected environment details
Example
```
const info = detectRuntime()
if (info.runtime === Runtime.Bun) {
  console.log(`Running on Bun ${info.version}`)
}
```
- Defined in runtime.ts:64