chore: import upstream snapshot with attribution

examples/pricing_e2e_check.rs

@@ -0,0 +1,26 @@
+//! Ad-hoc e2e check: fetch models.dev live and resolve a few model prices.
+//! Run: cargo run --example pricing_e2e_check
+fn main() {
+    jcode::model_pricing::schedule_refresh();
+    for _ in 0..100 {
+        std::thread::sleep(std::time::Duration::from_millis(200));
+        if let Some(c) = jcode::model_pricing::lookup("claude:api-key", "claude-fable-5") {
+            println!("fable-5: {:?}", c);
+            println!(
+                "deepseek-v4-flash: {:?}",
+                jcode::model_pricing::lookup("openai-compatible:deepseek", "deepseek-v4-flash")
+            );
+            println!(
+                "kimi-k2.5: {:?}",
+                jcode::model_pricing::lookup("openai-compatible:moonshotai", "kimi-k2.5")
+            );
+            println!(
+                "openrouter kimi: {:?}",
+                jcode::model_pricing::lookup("openrouter", "moonshotai/kimi-k2.5")
+            );
+            return;
+        }
+    }
+    eprintln!("TIMEOUT: no pricing after 20s");
+    std::process::exit(1);
+}