Remove --as-pid-1 from the bwrap invocation

bwrap now runs its own small reaper as pid 1 inside the sandbox
instead of execing the target command directly into that role.
-e/--exec is unaffected: it resolves the real namespace-holding child
dynamically via /proc rather than assuming any particular process
identity, so it still joins the right namespaces with the extra
reaper process in the tree.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gv3s5jckJKzh6JkMoi2Akz

src/bwrap.cpp

@@ -188,7 +188,6 @@ std::vector<std::string> build_bwrap_args(const std::string& root,
     std::vector<std::string> args = {"bwrap", "--die-with-parent"};
 
     auto unshare_args = detect_bwrap_unshare_args();
-    bool has_pid_ns = false;
     bool has_uts_ns = false;
     for (const auto& arg : unshare_args) {
         // Not requested yet: without any network setup (slirp4netns or similar),
@@ -200,15 +199,10 @@ std::vector<std::string> build_bwrap_args(const std::string& root,
             continue;
         }
         args.push_back(arg);
-        if (arg == "--unshare-pid") {
-            has_pid_ns = true;
-        } else if (arg == "--unshare-uts") {
+        if (arg == "--unshare-uts") {
             has_uts_ns = true;
         }
     }
-    if (has_pid_ns) {
-        args.push_back("--as-pid-1");
-    }
 
     if (hostname) {
         // bwrap itself refuses --hostname without --unshare-uts, so this must be