feat(nodejs): add namespace management methods on Connection (#3371)

### Summary

Closes #3363 

Adds the four namespace management methods to the NodeJS `Connection`,
bringing parity with the Rust core and Python bindings:

- `listNamespaces(parent?, options?)`
- `createNamespace(namespacePath, options?)`
- `dropNamespace(namespacePath, options?)`
- `describeNamespace(namespacePath)`

### Test plan
- npm test
- Ran a smoke test script

```typescript
import { connect } from '<lancePath>'
import { tmpdir } from "os";
import { mkdtempSync } from "fs";
import { join } from "path";

const dir = mkdtempSync(join(tmpdir(), "lancedb-smoke-"));
console.log(`Using temp dir: ${dir}\n`);

const db = await connect(dir, {
  namespaceClientProperties: { manifest_enabled: "true" },
});

console.log("Creating namespaces...");
await db.createNamespace(["analytics"]);
await db.createNamespace(["analytics", "sales"], {
  properties: { owner: "brendan", purpose: "smoke-test" },
});
await db.createNamespace(["marketing"]);

const root = await db.listNamespaces();
console.log("Root namespaces:", root.namespaces);

const children = await db.listNamespaces(["analytics"]);
console.log("Children of 'analytics':", children.namespaces);

const descWithProps = await db.describeNamespace(["analytics", "sales"]);
console.log("Describe analytics/sales (with properties):", descWithProps);

const descNoProps = await db.describeNamespace(["analytics"]);
console.log("Describe analytics (no properties):", descNoProps);

console.log("Describing a non-existent namespace (expect error)...");
try {
  await db.describeNamespace(["does-not-exist"]);
  console.error("  UNEXPECTED: describe succeeded for non-existent namespace");
} catch (err) {
  console.log(`  ✓ Got expected error: ${err.message.split("\n")[0]}`);
}

await db.dropNamespace(["marketing"]);
const afterDrop = await db.listNamespaces();
console.log("Root after dropping marketing:", afterDrop.namespaces);

await db.close();
console.log("\nAll operations completed successfully.");
```

```
Using temp dir: /var/folders/bj/hn6jv9c50y301d1nx0y8xmn00000gn/T/lancedb-smoke-MUC5NI

Creating namespaces...
Root namespaces: [ 'analytics', 'marketing' ]
Children of 'analytics': [ 'sales' ]
Describe analytics/sales (with properties): { properties: { purpose: 'smoke-test', owner: 'brendan' } }
Describe analytics (no properties): {}
Describing a non-existent namespace (expect error)...
  ✓ Got expected error: lance error: Namespace error: Namespace not found: does-not-exist, rust/lance-namespace-impls/src/dir/manifest.rs:2495:14  Caused by: Namespace error: Namespace not found: does-not-exist, rust/lance-namespace-impls/src/dir/manifest.rs:2495:14    Caused by: Namespace not found: does-not-exist
Root after dropping marketing: [ 'analytics' ]

All operations completed successfully.
```

### Documentation
- regenerated docs

nodejs/lancedb/connection.ts

@@ -16,6 +16,18 @@ import {
 } from "./arrow";
 import { EmbeddingFunctionConfig, getRegistry } from "./embedding/registry";
 import { Connection as LanceDbConnection } from "./native";
+import type {
+  CreateNamespaceResponse,
+  DescribeNamespaceResponse,
+  DropNamespaceResponse,
+  ListNamespacesResponse,
+} from "./native";
+export type {
+  CreateNamespaceResponse,
+  DescribeNamespaceResponse,
+  DropNamespaceResponse,
+  ListNamespacesResponse,
+};
 import { sanitizeTable } from "./sanitize";
 import { LocalTable, Table } from "./table";
 
@@ -110,6 +122,28 @@ export interface TableNamesOptions {
   /** An optional limit to the number of results to return. */
   limit?: number;
 }
+
+export interface ListNamespacesOptions {
+  /** Token from a previous response for pagination. */
+  pageToken?: string;
+  /** An optional limit to the number of results to return. */
+  limit?: number;
+}
+
+export interface CreateNamespaceOptions {
+  /** Creation mode. */
+  mode?: "create" | "exist_ok" | "overwrite";
+  /** Properties to set on the new namespace. */
+  properties?: Record<string, string>;
+}
+
+export interface DropNamespaceOptions {
+  /** Whether to skip if the namespace doesn't exist, or fail. */
+  mode?: "skip" | "fail";
+  /** Refuse to drop if non-empty (restrict) or drop recursively (cascade). */
+  behavior?: "restrict" | "cascade";
+}
+
 /**
  * A LanceDB Connection that allows you to open tables and create new ones.
  *
@@ -268,6 +302,69 @@ export abstract class Connection {
    */
   abstract dropAllTables(namespacePath?: string[]): Promise<void>;
 
+  /**
+   * Describe a namespace, returning its properties.
+   *
+   * @param {string[]} namespacePath - The namespace path to describe, in
+   *   parent → child order, e.g. `["analytics", "sales"]`.
+   * @returns {Promise<DescribeNamespaceResponse>} The namespace's properties
+   *   (may be undefined if the namespace has none).
+   */
+  abstract describeNamespace(
+    namespacePath: string[],
+  ): Promise<DescribeNamespaceResponse>;
+
+  /**
+   * List the immediate child namespaces under the given parent.
+   *
+   * Results may be paginated. To retrieve subsequent pages, pass the
+   * `pageToken` returned by a previous call.
+   *
+   * @param {string[]} namespacePath - The parent namespace path. Defaults
+   *   to the root namespace if omitted.
+   * @param {Partial<ListNamespacesOptions>} options - Pagination options
+   *   (`pageToken`, `limit`).
+   * @returns {Promise<ListNamespacesResponse>} Child namespace names and
+   *   an optional token for fetching the next page.
+   */
+  abstract listNamespaces(
+    namespacePath?: string[],
+    options?: Partial<ListNamespacesOptions>,
+  ): Promise<ListNamespacesResponse>;
+
+  /**
+   * Create a new namespace at the given path.
+   *
+   * @param {string[]} namespacePath - The namespace path to create.
+   * @param {Partial<CreateNamespaceOptions>} options - Creation `mode`
+   *   ("create" | "exist_ok" | "overwrite") and optional `properties`
+   *   to attach to the namespace.
+   * @returns {Promise<CreateNamespaceResponse>} The properties of the
+   *   created namespace and an optional transaction id.
+   */
+  abstract createNamespace(
+    namespacePath: string[],
+    options?: Partial<CreateNamespaceOptions>,
+  ): Promise<CreateNamespaceResponse>;
+
+  /**
+   * Drop a namespace.
+   *
+   * Use `behavior: "cascade"` to also drop everything contained in the
+   * namespace (sub-namespaces and tables). The default `"restrict"`
+   * behavior refuses to drop a non-empty namespace.
+   *
+   * @param {string[]} namespacePath - The namespace path to drop.
+   * @param {Partial<DropNamespaceOptions>} options - `mode` ("skip" | "fail"
+   *   for missing-namespace handling) and `behavior` ("restrict" | "cascade").
+   * @returns {Promise<DropNamespaceResponse>} Any properties returned by
+   *   the server and an optional transaction id.
+   */
+  abstract dropNamespace(
+    namespacePath: string[],
+    options?: Partial<DropNamespaceOptions>,
+  ): Promise<DropNamespaceResponse>;
+
   /**
    * Clone a table from a source table.
    *
@@ -515,6 +612,45 @@ export class LocalConnection extends Connection {
   async dropAllTables(namespacePath?: string[]): Promise<void> {
     return this.inner.dropAllTables(namespacePath ?? []);
   }
+
+  describeNamespace(
+    namespacePath: string[],
+  ): Promise<DescribeNamespaceResponse> {
+    return this.inner.describeNamespace(namespacePath);
+  }
+
+  listNamespaces(
+    namespacePath?: string[],
+    options?: Partial<ListNamespacesOptions>,
+  ): Promise<ListNamespacesResponse> {
+    return this.inner.listNamespaces(
+      namespacePath ?? [],
+      options?.pageToken,
+      options?.limit,
+    );
+  }
+
+  createNamespace(
+    namespacePath: string[],
+    options?: Partial<CreateNamespaceOptions>,
+  ): Promise<CreateNamespaceResponse> {
+    return this.inner.createNamespace(
+      namespacePath,
+      options?.mode,
+      options?.properties,
+    );
+  }
+
+  dropNamespace(
+    namespacePath: string[],
+    options?: Partial<DropNamespaceOptions>,
+  ): Promise<DropNamespaceResponse> {
+    return this.inner.dropNamespace(
+      namespacePath,
+      options?.mode,
+      options?.behavior,
+    );
+  }
 }
 
 /**

nodejs/lancedb/index.ts

@@ -62,6 +62,13 @@ export {
   CreateTableOptions,
   TableNamesOptions,
   OpenTableOptions,
+  ListNamespacesOptions,
+  CreateNamespaceOptions,
+  DropNamespaceOptions,
+  ListNamespacesResponse,
+  CreateNamespaceResponse,
+  DropNamespaceResponse,
+  DescribeNamespaceResponse,
 } from "./connection";
 
 export { Session } from "./native.js";