add csfloat api usage

BlueLaminate/BlueLaminate.Scraper/Proxies/IProxyProvider.cs

@@ -0,0 +1,21 @@
+namespace BlueLaminate.Scraper.Proxies;
+
+/// <summary>
+/// Source of proxy endpoints. The whole point of this seam is that the rest of
+/// the scraper depends only on this interface and <see cref="ProxyLease"/>, so a
+/// different residential provider — or the future C2 that allocates IPs to
+/// containers, or a composite "grab-bag" over several providers — drops in
+/// without changing any browser or scraping code.
+/// </summary>
+public interface IProxyProvider
+{
+    /// <summary>Identifier recorded on issued leases, e.g. "iproyal".</summary>
+    string Name { get; }
+
+    /// <summary>
+    /// Produce a usable endpoint for the given request. For gateway providers
+    /// this is pure string composition (no network call); the C2 implementation
+    /// can override that later with real allocation.
+    /// </summary>
+    ProxyLease Acquire(ProxyRequest request);
+}