font: fix nerd font patcher ypadding twice what it should be (#7841)

The nerd font patcher uses `ypadding` as a single subtraction from the
cell height, which means that half of it should go to the top padding
and the other half to the bottom, but we were setting it for both the
top and bottom! This was making the heavy brackets way too small lol
(0.4 of the cell height instead of 0.7)

#7834 introduced the *opposite* problem to what it fixed haha. This
fixes it for real!

src/font/nerd_font_attributes.zig

@@ -40,8 +40,8 @@ pub fn getConstraint(cp: u21) Constraint {
             .max_constraint_width = 1,
             .align_horizontal = .center,
             .align_vertical = .center,
-            .pad_top = 0.3,
-            .pad_bottom = 0.3,
+            .pad_top = 0.15,
+            .pad_bottom = 0.15,
         },
         0xe0b0,
         => .{

src/font/nerd_font_codegen.py

@@ -213,8 +213,8 @@ def emit_zig_entry_multikey(codepoints: list[int], attr: PatchSetAttributeEntry)
         s += f"            .pad_top = {v_pad},\n"
         s += f"            .pad_bottom = {v_pad},\n"
     elif y_padding:
-        s += f"            .pad_top = {y_padding},\n"
-        s += f"            .pad_bottom = {y_padding},\n"
+        s += f"            .pad_top = {y_padding / 2},\n"
+        s += f"            .pad_bottom = {y_padding / 2},\n"
 
     if xy_ratio > 0:
         s += f"            .max_xy_ratio = {xy_ratio},\n"