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/kb_text_shape/kb_text_shape.sx

@@ -0,0 +1,18 @@
+// =====================================================================
+// vendors/kb_text_shape — Jimmy Lefevre's kb_text_shape (OpenType text
+// shaping) as a `#import c` unit (c/, see README.md for version +
+// provenance).
+//
+// `#import "vendors/kb_text_shape/kb_text_shape.sx"` gives any sx
+// program text shaping with no system dependency. The decls come from
+// c/kbts_api.h — a hand-curated MINIMAL declaration header covering
+// only the bound surface (the full upstream header is ~30k lines and
+// is included only by the implementation unit). Shape contexts, fonts,
+// runs, and glyphs are opaque pointers on the sx side; see
+// modules/ui/glyph_cache.sx for the reference consumer.
+// =====================================================================
+
+#import c {
+    #include "c/kbts_api.h";
+    #source  "c/kb_text_shape_impl.c";
+};