Add headless session and UTF-8 buffer core

src/main.zig

@@ -1,4 +1,5 @@
 const std = @import("std");
+const session = @import("session.zig");
 
 pub const version = "0.1.0-dev";
 
@@ -62,6 +63,10 @@ pub fn main(init: std.process.Init) !u8 {
     return 0;
 }
 
+test {
+    _ = session;
+}
+
 test "regular: help text names the binary and smoke boundary" {
     try std.testing.expect(std.mem.indexOf(u8, help_text, "mim - mobile-first terminal code editor") != null);
     try std.testing.expect(std.mem.indexOf(u8, help_text, "canonical smoke path") != null);