fix(core): spawn shell non-interactively without sourcing rc files

ShellSelect.args() ran zsh/bash with -l and explicitly sourced .zshrc/.bashrc,
loading user functions and aliases that can shadow builtins and return non-zero
exit codes, breaking && chains. Match the old tool behavior: plain non-login
non-interactive shell -c command with cwd passed via spawn options.

packages/opencode/src/session/prompt.ts

@@ -521,7 +521,7 @@ export const layer = Layer.effect(
 
           const cfg = yield* config.get()
           const sh = ShellSelect.preferred(cfg.shell)
-          const args = ShellSelect.args(sh, input.command, cwd)
+          const args = ShellSelect.args(sh, input.command)
           let output = ""
           let aborted = false