Restore Remote-SSH support for 32-bit ARM Linux (armv7l) targets

Since VS Code 1.86 removed the Linux ARM32 (armv7l) server build, Remote-SSH can no longer connect to 32-bit ARM devices. Connecting fails with:

Error: CodeError(UnsupportedPlatform("LinuxARM32"))

Steps:
1. Windows PC with current VS Code (1.86+) and Remote-SSH extension
2. Target: Raspberry Pi running 32-bit Raspberry Pi OS (armv7l)
3. Remote Explorer -> connect via SSH to the Pi
4. Connection fails with UnsupportedPlatform("LinuxARM32"); "Downloading VS Code Server..." notifications hang indefinitely with repeated password prompts

Expected: Able to connect and use Remote-SSH as before 1.86.

Impact: In industrial/embedded environments, many devices must stay on 32-bit OS images because vendor applications are compiled for armhf and cannot be rebuilt. Reflashing to 64-bit is not an option. Downgrading the Remote-SSH extension does not help since the server build itself no longer exists, and pinning VS Code at 1.85.2 permanently is not sustainable.

Request: Reinstate the ARM32 server build, or provide an officially supported lightweight/legacy server option for armv7l targets so these devices remain reachable for editing and debugging.

The issue names no repository files, tests, or entry points. Start by locating the Remote-SSH server platform/download handling and the LinuxARM32 error path, then determine whether an ARM32 build or a supported legacy option is feasible. Done means a 32-bit armv7l target can connect and the relevant regression coverage passes.

Written by the indexing model from the issue text.