sqlite bindings: cite sx issue 0128 for the ?[:0]u8 boundary

src/db/sqlite.sx

@@ -38,10 +38,11 @@
 // `prepare_v2/v3` and `bind_text/blob` take `[*]u8` + explicit byte
 // length instead, so un-terminated sx string views pass without
 // copying. Nullable C strings OUT are `?*u8` — the null lives in the
-// type (`?[:0]u8` would be ideal but does not resolve in sx yet, and a
+// type. `?[:0]u8` is the contract these should carry (a nullable thin
-// sentinel-slice return would need a synthesized strlen) — and are
+// char*), but [:0]u8 returns/optionals don't cross the FFI correctly
-// COPIED into `context.allocator` before returning — sqlite's buffers
+// yet — sx issue 0128. Returned strings are COPIED into
-// die on the next step/finalize/close.
+// `context.allocator` before returning — sqlite's buffers die on the
+// next step/finalize/close.
 // =====================================================================
 
 #import "modules/std.sx";