fix(managed): report ExportedType rows in managed member inspection (#1828)

* fix(managed): report ExportedType rows in managed member inspection

Facade assemblies such as System.Runtime.dll provide their types only
through ExportedType rows (type forwarders), which member inspection
never read, so they reported complete coverage with no types. Report
each row as declared with its flags, forwarder bit, TypeDefId hint, and
implementation token, and record invalid or null implementation coded
indexes as partial coverage. Comparisons now state that exported types
are not compared when either side has them.

Fixes #1812

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(managed): read earlier member Evidence without exported types

Member Evidence recorded before ExportedType rows were read omits the
field. Parse it as null (not examined) instead of rejecting it, and
state in comparisons that such an observation's exported types are
unknown.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(managed): leave exported types unknown when metadata is unavailable

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

docs/managed-code-analysis.md

@@ -126,6 +126,15 @@ Member inspection binds build-local tokens, signatures, row offsets, method
 bodies, and decoded relationships to that artifact and MVID. Missing or malformed
 facts remain explicit in coverage and per-member status.
 
+`exported_types` reports ExportedType rows as declared. Facade assemblies such
+as .NET `System.Runtime.dll` provide their types this way: `forwarder: true`
+marks a type forwarder, and `implementation_token` names the AssemblyRef, File,
+or enclosing ExportedType row that implements it. REA does not load the
+implementing assembly to resolve the forwarded definition, and
+`compare_managed_members` does not compare exported types. Member Evidence
+recorded before this field existed reads back with `exported_types: null`,
+which means the table was not examined.
+
 CLI `#GUID` heap values retain their exact 16-byte GUID text. REA does not impose
 RFC 4122 UUID version or variant bits on MVID, EncId, or EncBaseId because
 ECMA-335 metadata does not require those bit patterns. Tokens and RVAs are