fix pkg size returning blank: resolve nixpkgs#<pkg> (bare name isn't a valid installable) and report human-readable closure size

@@ -635,13 +635,22 @@635635 }636636 637637 pub fn pkgSize(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine, pkg: []const u8) ![]u8 {638-    const r = try capture(gpa, io, machine, &.{ "nix", "path-info", "-s", pkg });638+    // A bare name ("ripgrep") isn't a valid installable; resolve via nixpkgs# like639+    // `pkg path` does. -S -h gives closure size, human-readable. Output is640+    // "<store-path>   <size>"; return just the size.641+    const ref = try std.fmt.allocPrint(gpa, "nixpkgs#{s}", .{pkg});642+    defer gpa.free(ref);643+    const r = try capture(gpa, io, machine, &.{ "nix", "path-info", "-S", "-h", ref });639644     defer gpa.free(r.stderr);640-    if (r.exit_code != 0) {641-        gpa.free(r.stdout);642-        return error.ProcessFailed;643-    }644-    return r.stdout;645+    defer gpa.free(r.stdout);646+    if (r.exit_code != 0) return error.ProcessFailed;647+648+    const line = std.mem.trim(u8, r.stdout, " \t\n\r");649+    var it = std.mem.tokenizeAny(u8, line, " \t");650+    _ = it.next(); // store path651+    const size = std.mem.trim(u8, it.rest(), " \t");652+    if (size.len == 0) return error.ProcessFailed;653+    return gpa.dupe(u8, size);645654 }646655 647656 pub fn pkgClosure(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, pkg: []const u8) !u8 {