docs(workspace): document table-export endpoint for Snowflake and BigQuery

DMD-1332

Add a new page describing POST /v2/storage/workspaces/{id}/table-export,
its request/response, supported backends (Snowflake + BigQuery),
formats (CSV + Parquet + gzip), and limitations. Link to it from the
Unloading Data section of the workspace index.

Pairs with keboola/connection#7188.

Author: vojtabiberle

workspace/index.md

@@ -294,6 +294,10 @@ or [File Output Mapping](/transformations/mappings/#file-output-mapping) (or bot
 Unloading data is useful, for example, when your ad-hoc analysis leads to
 valuable results, or when you trained a new model which you'd like to use in transformations.
 
+For Snowflake and BigQuery workspaces, you can also export a single table directly from the workspace schema to
+[File Storage](/storage/files/) via the Storage API. See
+[Exporting Workspace Tables to Files](/workspace/table-export/) for details.
+
 ### Data Persistency (beta)
 When this feature is enabled in a project, your data in workspaces can be kept. This way you can, when you return, start where you left off without losing data or time by importing the data again or executing scripts to get to the right stage.
 

workspace/table-export.md

@@ -0,0 +1,82 @@
+---
+title: Exporting Workspace Tables to Files
+permalink: /workspace/table-export/
+---
+
+* TOC
+{:toc}
+
+You can export a table that lives in a Snowflake or BigQuery workspace schema to [File Storage](/storage/files/)
+via the Storage API. The export runs as an asynchronous storage job, and the job result contains the file ID of the
+exported file, which can then be downloaded like any other Keboola file.
+
+This is useful when you build data in a workspace (for example, via the [SQL Editor](/workspace/sql-editor/) or a
+custom integration) and need to move the resulting table outside of the workspace without going through Storage
+output mapping.
+
+Currently supported backends:
+
+- **Snowflake**
+- **BigQuery**
+
+## Endpoint
+
+```
+POST https://connection.keboola.com/v2/storage/workspaces/{workspace_id}/table-export
+X-StorageApi-Token: your_token
+Content-Type: application/json
+
+{
+    "tableName": "my_table",
+    "fileName": "custom_export",
+    "fileType": "csv",
+    "gzip": true
+}
+```
+
+### Request Body
+
+| Field       | Type    | Required | Description                                                                                |
+|-------------|---------|----------|--------------------------------------------------------------------------------------------|
+| `tableName` | string  | yes      | Name of the table (or view) to export from the workspace schema.                           |
+| `fileName`  | string  | yes      | Name that will be used for the resulting file in File Storage.                             |
+| `fileType`  | string  | no       | Output format: `csv` (default) or `parquet`.                                               |
+| `gzip`      | boolean | no       | When `true`, the exported file is gzip-compressed. Default `false`. Ignored for Parquet.   |
+
+### Response
+
+The endpoint returns a standard asynchronous [storage job](/overview/#storage-jobs) with HTTP 202. When the job
+finishes, its `results` contain the ID of the exported file:
+
+```json
+{
+    "file": {
+        "id": 12345678
+    }
+}
+```
+
+Download the file with the standard [file download](/integrate/storage/api/importer/#download-a-file) flow.
+
+## Backend-Specific Notes
+
+### Snowflake
+
+- Supports **CSV** and **Parquet**.
+- Works with all project file storage providers (AWS S3, Azure Blob Storage, Google Cloud Storage).
+
+### BigQuery
+
+- Supports **CSV** and **Parquet**.
+- Available for BigQuery projects only; the exported file always lands in the project's GCS file storage.
+
+## Limitations
+
+- The workspace must be a **table workspace**. File/Python/R workspaces are not supported.
+- **Reader account** workspaces cannot export data through this endpoint.
+- The workspace must use a supported backend (Snowflake or BigQuery).
+
+## API Reference
+
+See the full request/response specification in the
+[Storage API reference](https://keboolastorageapi.docs.apiary.io/#reference/workspaces/export-table-from-workspace/export-table-from-workspace).