library: vendors/kb_text_shape + vendors/file_utils; modules/ffi/stb_truetype.sx retired

kb_text_shape (v2.10, JimmyLefevre) had been LOST from the sx tree —
ffi/stb_truetype.sx referenced repo paths that no longer existed (and
nothing runs glyph_cache, so the dangling unit never fired). The
trimmed copy returns from the m3te project as a proper vendor:
curated c/kbts_api.h decls over the full upstream header, README with
provenance, and examples/1627 pinning context + font creation so the
unit compiles and runs in-suite. file_utils (in-house asset-read
helper with the Android AAssetManager hook) gets the same unit shape.

modules/ffi/stb_truetype.sx is gone: glyph_cache imports the three
vendored units (stb_truetype, kb_text_shape, file_utils) directly.

library/vendors/file_utils/file_utils.sx

@@ -0,0 +1,12 @@
+// =====================================================================
+// vendors/file_utils — in-house C helper: `read_file_bytes` with an
+// Android twist. On most platforms it is a plain stdio read; on
+// Android, paths rooted inside the APK resolve through the
+// AAssetManager installed via `sx_android_set_asset_manager`
+// (modules/platform/android.sx wires that during activity startup).
+// =====================================================================
+
+#import c {
+    #include "c/file_utils.h";
+    #source  "c/file_utils.c";
+};