env fix

    // overrides, then the make-special variables that must exist before parsing.

    auto load_makefile = [&](makeplus::Makefile& m) -> bool {

        setup_defaults(m, argv[0]);

        // GNU make's own documented behavior (never implemented here before):

        // every variable in the process's environment becomes a make

        // variable, as if the makefile had a plain "NAME = value" assignment

        // for each one -- so it's visible as $(NAME), AND (critically) a

        // real assignment for that same name written INSIDE the makefile

        // still overrides it normally, exactly like any other variable

        // redefinition. Real-world case this fixes: kernel.spec's own

        // "export WERROR=0" (meant to disable tools/lib/subcmd's own

        // -Werror, which THAT makefile gates behind "ifneq ($(WERROR),0)")

        // silently did nothing -- $(WERROR) was always empty, since nothing

        // here ever consulted the environment for a plain variable lookup at

        // all (only MAKEFLAGS, elsewhere, for its own separate reasons) --

        // so the ifneq was always true and -Werror always got added, no

        // matter what the invoking shell exported. from_cmdline=false here

        // is exactly what already lets an ordinary "VAR = value" line

        // inside the makefile overwrite it further down in parse_file()

        // (which already gates a same-name redefinition on that flag to

        // protect a REAL command-line override, e.g. "make VAR=x", from

        // being silently clobbered by the makefile's own text) -- an

        // environment-sourced default is supposed to lose to either, unlike

        // a command-line one.

        for (char** e = environ; *e; ++e) {

            const char* eq = std::strchr(*e, '=');

            if (!eq || eq == *e) continue;

            std::string name(*e, eq - *e);

            m.variables[name] = {std::string(eq + 1), makeplus::VarFlavor::Recursive, false};

        }

        // Command-line variables have the highest priority.

        for (const auto& [name, value] : cmdline_vars)

            m.variables[name] = {value, makeplus::VarFlavor::Simple, true};