feat: support per-request header override (#2631)

## Summary

This PR introduces a `HeaderProvider` which is called for all remote
HTTP calls to get the latest headers to inject. This is useful for
features like adding the latest auth tokens where the header provider
can auto-refresh tokens internally and each request always set the
refreshed token.

---------

Co-authored-by: Claude <noreply@anthropic.com>

nodejs/src/connection.rs

@@ -2,12 +2,14 @@
 // SPDX-FileCopyrightText: Copyright The LanceDB Authors
 
 use std::collections::HashMap;
+use std::sync::Arc;
 
 use lancedb::database::CreateTableMode;
 use napi::bindgen_prelude::*;
 use napi_derive::*;
 
 use crate::error::NapiErrorExt;
+use crate::header::JsHeaderProvider;
 use crate::table::Table;
 use crate::ConnectionOptions;
 use lancedb::connection::{ConnectBuilder, Connection as LanceDBConnection};
@@ -45,7 +47,11 @@ impl Connection {
 impl Connection {
     /// Create a new Connection instance from the given URI.
     #[napi(factory)]
-    pub async fn new(uri: String, options: ConnectionOptions) -> napi::Result<Self> {
+    pub async fn new(
+        uri: String,
+        options: ConnectionOptions,
+        header_provider: Option<&JsHeaderProvider>,
+    ) -> napi::Result<Self> {
         let mut builder = ConnectBuilder::new(&uri);
         if let Some(interval) = options.read_consistency_interval {
             builder =
@@ -57,8 +63,16 @@ impl Connection {
             }
         }
 
+        // Create client config, optionally with header provider
         let client_config = options.client_config.unwrap_or_default();
-        builder = builder.client_config(client_config.into());
+        let mut rust_config: lancedb::remote::ClientConfig = client_config.into();
+
+        if let Some(provider) = header_provider {
+            rust_config.header_provider =
+                Some(Arc::new(provider.clone()) as Arc<dyn lancedb::remote::HeaderProvider>);
+        }
+
+        builder = builder.client_config(rust_config);
 
         if let Some(api_key) = options.api_key {
             builder = builder.api_key(&api_key);