Scan for globals in c_program(). During the first pass (which finds function definitions), also collect top-level var declarations:

At the top of c_program(), before scanning for functions:

    // Scan for top-level globals
    c_global_count = 0;
    source = input;
    pos = 0;
    skip();
    var brace_depth: i32 = 0;
    while (pos < source.len) {
        if (source[pos] == '{') { brace_depth += 1; pos += 1; continue; }
        if (source[pos] == '}') { brace_depth -= 1; pos += 1; continue; }
        if (brace_depth == 0 and is_letter(cur())) {
            const s: usize = pos;
            const w: []const u8 = read_name();
            if (streq(w, "var") or streq(w, "const")) {
                const vn: []const u8 = read_name();
                if (cur() == ':') { pos += 1; skip(); _ = read_name(); }
                c_global_names[c_global_count] = vn;
                c_global_count += 1;
            } else if (streq(w, "fn")) {
                // skip entire fn (will be handled in function pass)
                while (cur() != '{' and cur() != 0) { pos += 1; }
                if (cur() == '{') { skip_block(); }
            } else {
                pos = s;
                pos += 1;
            }
        } else {
            pos += 1;
        }
    }

Then emit the global declarations:

    for (0..c_global_count) |i| {
        emit_str("(global $");
        emit_str(c_global_names[i]);
        emit_str(" (mut i64) (i64.const 0))\n");
    }