effect(util): make Process.run/text/lines return Effect

Migrate the run/text/lines helpers in util/process.ts to Effect-returning
functions that yield ChildProcessSpawner and use ChildProcess.make
internally. The legacy Promise-based behaviour stays available under
runPromise/textPromise/linesPromise for non-Effect callers; these are
thin wrappers over the original spawn() path so AbortSignal and timeout
semantics are preserved.

server.ts now runs Process.run/Process.text through a private
ManagedRuntime backed by CrossSpawnSpawner.defaultLayer and the shared
memoMap, since LSP.spawn callbacks execute inside Effect.promise blocks.

Other Process.run/text/lines call sites are renamed to the *Promise
variants and otherwise left untouched for follow-up migrations.