fix(fonttools): record the TrueType on-curve flag per point

_pon was never written, so every point was treated as off-curve and all
straight edges/corners were flattened through the quadratic path. Set
_pon from bit 0 of each parsed glyph flag, including repeated flags.

vpsdk/fonttools/fonttools.vp

@@ -361,6 +361,7 @@ def _add_glyph(font: Font*, gid: int, a: float, b: float, c: float, d: float, tx
             f: uint8 = _u8(base, p)
             p += 1
             _flags[i] = f
+            _pon[i] = f & 1
             i += 1
             if f & 8:
                 rep: int = int(_u8(base, p))
@@ -368,6 +369,7 @@ def _add_glyph(font: Font*, gid: int, a: float, b: float, c: float, d: float, tx
                 for k in range(rep):
                     if i < npts:
                         _flags[i] = f
+                        _pon[i] = f & 1
                         i += 1
         x: int = 0
         for i in range(npts):