refactor: grid and timer using zephr

todo.txt

@@ -1,5 +1,20 @@
 - "premade" (but also customizable) ui elements (buttons, text boxes, etc) with instanced rendering
 - border decorations for shapes (maybe. or maybe only for ui elements)
+- some kind of ui layout/hierarchy system (for later, when we actually need it)
+- grid texture (draw_image? or draw_texture? func)
+
+- sooo a bit of a problem... since we render all our text in one draw call
+  at the end of the frame. this means that we can't have text that's rendered
+  in behind anything else. This needs to be fixed because drawing any overlay
+  will result in all the text being drawn OVER everything else, which might not be
+  the desired behavior at times (e.g. help/win overlay where the board numbers need to be
+  rendered under the overlay(s))
+  - possible solutions :Clueless:
+    - z-index based on the order of creation (e.g. the first drawable created has the lowest z-index)
+      I _think_ this works because we can just chuck a global z-index whenever we call
+      draw_text or draw_quad/etc.. and the shader _should_ take care of everything
+    - every draw_text call actually makes a single draw call (compromises on performance but way easier to use)
+
 
 text rendering improvements
   - [ ] unicode support (allows for non-ascii characters)