fix(android): default unknown invoke coverage to JSON null

Keep direct_invokes_exhaustive normalization in the Android result contract so its parsed output is JSON-safe. Omitted or explicitly undefined provider coverage becomes null, while false and true remain distinct. Preserve the exact DEX descriptor and direct-invoke evidence introduced by PR #2439.

Backports the Android-only part of main commit 6e25cc3c76 for older PR branches. Captured main already contains this behavior. Tests, checks, builds, typechecks, lint and CI reruns were intentionally skipped at user request; inspected the producing protocol, adapter mapping and named result contract.

Co-authored-by: LcokHcak <j1637848276@gmail.com>

src/domain/android/androidAnalysis.ts

@@ -188,7 +188,7 @@ export const androidResultSchemas = {
         source_line: z.null(),
         dex_offset: z.null(),
         /** false means transport-bounded instruction evidence; null/omitted is unknown. */
-        direct_invokes_exhaustive: z.boolean().nullable().optional(),
+        direct_invokes_exhaustive: z.boolean().nullable().default(null),
         /** Raw direct invoke instructions inside this using node, when available. */
         direct_invokes: z
           .array(