feat(provenance): add FreeType renderer version

Record the linked FreeType library version beside the CrossGlyph and
cpfont format versions. This identifies the rasterizer that produced the
glyphs instead of relying on the freetype-py package version.

Verified with the provenance tests, prose check, and the full CrossGlyph
suite.

Author: CrazyCoder

docs/fonts.md

@@ -1000,6 +1000,7 @@ to somebody who liked how it looked, and what travels with it is four
 "built": {
   "at": "2026-08-15T08:44:43Z",
   "by": "crossglyph X.Y.Z",
+  "freetype": "X.Y.Z",
   "cpfont_format": 4,
   "config": "bitter.conf",
   "settings": {"gamma": 1.0, "hinting": "light", "figures": "proportional", …},
@@ -1024,6 +1025,9 @@ Every setting, including the ones no config set. Defaults move between
 versions, so a record of the departures alone would reproduce a different font
 later, and neither copy could say which one shipped.
 
+`freetype` is the version of FreeType that drew the glyphs, read from the
+library itself rather than from the Python package that loads it.
+
 Some of it serves a reader instead of a rebuild. `sha256` settles whether the
 face you have is the face this was made from, where a version string is a claim
 and a filename is a label. `licence_url` and `designer` answer the first two

src/crossglyph/provenance.py

@@ -23,6 +23,8 @@
 import pathlib
 import typing
 
+import freetype
+
 from . import cpfont, fontstamp, version
 from .fontconf import STYLES, Config, Variant, size_label, variable_font
 
@@ -220,6 +222,7 @@ def describe(variant: Variant, directory: pathlib.Path,
     return {
         "at": stamped.replace(microsecond=0).isoformat().replace("+00:00", "Z"),
         "by": f"crossglyph {version.installed()}",
+        "freetype": ".".join(map(str, freetype.version())),
         "cpfont_format": cpfont.CPFONT_VERSION,
         "config": config.path.name,
         "settings": _settings(variant),

tests/test_provenance.py

@@ -6,6 +6,7 @@
 """
 import json
 
+import freetype
 import pytest
 
 from crossglyph import fontbuild, fontconf, fontstamp, provenance
@@ -79,6 +80,7 @@ def test_it_says_what_made_it(built):
 
     made = built["built"]
     assert made["by"] == f"crossglyph {version.installed()}"
+    assert made["freetype"] == ".".join(map(str, freetype.version()))
     assert made["cpfont_format"] == fontbuild.cpfont.CPFONT_VERSION
     assert made["config"] == "probe.conf"
     assert made["at"].endswith("Z")