Add support for SerialComputerNames CSV mapping

Introduces a new `SerialComputerNames` device naming mode that allows automated device naming during deployment based on the BIOS serial number. The mapping is provided via a CSV file with `SerialNumber` and `ComputerName` columns.

This feature requires `CopyUnattend` and writes a `SerialComputerNames.csv` file to the USB deployment media, replacing the need for manual prompts or prefix selection when device serial numbers are known in advance. The UI has been updated to support creating, loading, and saving the CSV mapping content.

docs/build.md

@@ -340,7 +340,7 @@ This option is primarily intended for scenarios where:
 
 | Limitation                        | Description                                                                                                                                              |
 | --------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| **No prefixes.txt or %serial% support** | Unlike **Copy Unattend.xml**, this method does not support `prefixes.txt` or the `%serial%` variable for deployment-time device naming |
+| **No prefixes.txt, SerialComputerNames.csv, or %serial% support** | Unlike **Copy Unattend.xml**, this method does not support `prefixes.txt`, `SerialComputerNames.csv`, or the `%serial%` variable for deployment-time device naming |
 | **Fixed configuration**     | The unattend settings are baked into the FFU at build time and cannot be changed at deployment time                                                      |
 | **Requires VM to be built** | This option only works when**Install Apps** is `$true` because the unattend file is included in the Apps ISO                                     |
 
@@ -348,7 +348,7 @@ This option is primarily intended for scenarios where:
 
 > Note
 >
-> Most users should continue using the **Copy Unattend** option via the USB drive, which provides more flexibility including support for `prefixes.txt` device naming. Use **Inject Unattend.xml** only when you won't be using the USB drive for deployment.
+> Most users should continue using the **Copy Unattend** option via the USB drive, which provides more flexibility including support for `prefixes.txt`, `SerialComputerNames.csv`, and `%serial%` device naming. Use **Inject Unattend.xml** only when you won't be using the USB drive for deployment.
 
 {: .tip-title}
 
@@ -423,6 +423,37 @@ Use **Prefixes File Path** to point the UI at the source text file for the prefi
 
 Use **Save Prefixes** to write the current multiline prefixes list back to the file specified in **Prefixes File Path**.
 
+### Specify Serial to Device Name Mapping
+
+This option writes `SerialComputerNames.csv` from the CSV content in the UI. Use `SerialNumber,ComputerName` as the header row, then add one row per device. During deployment, `ApplyFFU.ps1` compares the current BIOS serial number to the `SerialNumber` column and uses the matching `ComputerName` value.
+
+Sample `SerialComputerNames.csv` content:
+
+```plaintext
+SerialNumber,ComputerName
+ABC12345,CORP-001
+DEF67890,KIOSK-010
+XYZ24680,STORE-015
+```
+
+- This option requires **Copy Unattend.xml**.
+- **Inject Unattend.xml** is not supported with this option.
+- If no matching serial number is found during deployment, `ApplyFFU.ps1` falls back to a random `FFU-*` computer name so setup can finish.
+
+{: .note-title}
+
+> Note
+>
+> If `prefixes.txt` and `SerialComputerNames.csv` are both staged manually on the same deployment media, `ApplyFFU.ps1` checks `prefixes.txt` first. FFU Builder avoids this conflict by only staging the naming file for the selected device-naming mode.
+
+### SerialComputerNames.csv File Path
+
+Use **SerialComputerNames.csv File Path** to point the UI at the source CSV file for the serial-to-device-name mapping. The file can use any name. When you browse to a mapping file in the UI, or when a saved configuration references a valid CSV path, the UI loads that file and populates the multiline CSV box from its contents.
+
+### Save Serial Mapping
+
+Use **Save Serial Mapping** to write the current CSV content back to the file specified in **SerialComputerNames.csv File Path**.
+
 ### Deployment Prompt Compatibility
 
 Older deployment media that already has an unattend file with `ComputerName` set to the legacy placeholder value and no `prefixes.txt` file will still prompt for a device name during deployment.
@@ -443,8 +474,9 @@ The `.\FFUDevelopment\Unattend` folder includes sample files you can customize:
 | **unattend_x64.xml**       | Active unattend file used for x64 builds   |
 | **unattend_arm64.xml**     | Active unattend file used for arm64 builds |
 | **SamplePrefixes.txt**     | Example prefixes file for device naming    |
+| **SampleSerialComputerNames.csv** | Example serial-to-device-name CSV file |
 
-Copy and customize the sample files to create your own `unattend_x64.xml`, `unattend_arm64.xml`, and `prefixes.txt` files.
+Copy and customize the sample files to create your own `unattend_x64.xml`, `unattend_arm64.xml`, `prefixes.txt`, and `SerialComputerNames.csv` files.
 
 {: .note-title}
 
@@ -537,12 +569,13 @@ When enabled, the build process copies:
 
 - The selected x64 or arm64 unattend XML file → renamed to **Unattend.xml** on the USB drive
 - **prefixes.txt** → created from the **Device Naming** prefixes list when that mode is selected
+- **SerialComputerNames.csv** → created from the **Device Naming** serial mapping list when that mode is selected
 
 If you keep the default file paths in place, FFU Builder uses `unattend_x64.xml` for x64 builds and `unattend_arm64.xml` for arm64 builds.
 
 During deployment, `ApplyFFU.ps1` applies `Unattend.xml` whenever it is present. Device naming only happens when the **Device Naming** setting requires it, or when older media still uses the legacy prompt-based workflow.
 
-See **Device Naming Expander** above for the available computer-name modes and prefixes-file behavior.
+See **Device Naming Expander** above for the available computer-name modes and naming-file behavior.
 
 ### Copy Provisioning Package