fix(router): support BigInt in query parameters (#89213)
**What changed?**
`stringifyUrlQueryParam` now handles `bigint` type properly.
**Why?**
BigInt is a valid JavaScript primitive but was being converted to empty
string:
Before:
```js
stringifyUrlQueryParam(123n) // '' ❌
```
After:
```js
stringifyUrlQueryParam(123n) // '123' ✓
```
**Use case:**
Query parameters with large integers (IDs, timestamps) often use BigInt
to avoid precision loss.
**Testing**
Manual testing with BigInt values.
