Function validateAndPingUrl

validateAndPingUrl(
    targetUrl: string,
    proxyBase?: string,
    timeoutMs?: number,
): Promise<PingResult>
Validates a URL's syntax and tests whether the server is reachable.

Strategy:
1. HEAD → 2xx/3xx → reachable, no proxy needed.
2. HEAD → 4xx/5xx → server is alive but the bare path fails. Try OGC GetCapabilities directly (CORS was fine since HEAD got a response). If valid → reachable. Otherwise → not reachable.
3. HEAD → CORS → server is alive but blocks cross-origin. Try OGC GetCapabilities through the proxy. If valid → reachable + needsProxy. Otherwise → not reachable.
4. HEAD → network/timeout → server unreachable.
The function never throws — all failures are returned as part of the result object.
Parameters
- targetUrl: string
  The URL to validate and ping
- proxyBase: string = CONFIG_PROXY_URL
  Optional proxy server base URL (defaults to CONFIG_PROXY_URL)
- timeoutMs: number = 5000
  Optional request timeout in milliseconds (defaults to 5000ms)
Returns Promise<PingResult>
A promise that resolves with a result object containing isValid, isReachable, needsProxy, status, and optional error
- Defined in packages/geoview-core/src/core/utils/utilities.ts:492