Add conformance tests and fix introspection issues

- Add conformance test framework with poe conformance task
- Add test files for mathutils, bpy, and gpu API patterns
- Fix self param leaking into signatures from C method_descriptors
- Synthesize __iter__ for classes with __getitem__ but no explicit __iter__
- Add __iter__ runtime probing to discover Iterator[element_type]
- Add :raises to directive lookahead to fix rtype parsing
- Add 5.1 override for Matrix.Translation to accept Vector

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

overrides/5.1/mathutils.json

@@ -0,0 +1,7 @@
+{
+  "Matrix.Translation": {
+    "params": {
+      "vector": "Sequence[float] | Vector"
+    }
+  }
+}