fix: restrict terminal childProcess.spawn to local-only environments (#10538)

fix: restrict childProcess.spawn to local-only environments

childProcess.spawn executes on the extension host machine. With
extensionKind: ["ui", "workspace"], the extension host almost always
runs locally. For any remote workspace (SSH, WSL, Dev Container,
Codespaces, tunnel), spawning locally either runs commands on the wrong
machine or fails with ENOENT when the local shell doesn't exist in the
extension host context.

Replace ENABLED_FOR_REMOTES (which listed all remote types) with
LOCAL_ONLY (just "" and "local"). All remote types now fall through to
ide.runCommand() which delegates to VS Code's integrated terminal and
executes in the correct remote environment.

The isWindowsHostWithRemote guard is removed as it is now redundant —
the platform-agnostic check handles all cases.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>