Python API improvements: Vectors, bounds, window singleton, hidden types

- #177: GridPoint.grid_pos property returns (x, y) tuple
- #179: Grid.grid_size returns Vector instead of tuple
- #181: Grid.center returns Vector instead of tuple
- #182: Caption.size/w/h read-only properties for text dimensions
- #184: mcrfpy.window singleton for window access
- #185: Removed get_bounds() method, use .bounds property instead
- #188: bounds/global_bounds return (pos, size) as pair of Vectors
- #189: Hide internal types from module namespace (iterators, collections)

Also fixed critical bug: Changed static PyTypeObject to inline in headers
to ensure single instance across translation units (was causing segfaults).

Closes #177, closes #179, closes #181, closes #182, closes #184, closes #185, closes #188, closes #189

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_frame_bounds.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+"""Test Frame bounds"""
+import sys
+import mcrfpy
+
+print("Testing Frame bounds...")
+frame = mcrfpy.Frame(pos=(50, 100), size=(200, 150))
+
+print(f"Frame created: {frame}")
+
+# Test bounds returns tuple of Vectors
+bounds = frame.bounds
+print(f"bounds type: {type(bounds)}")
+print(f"bounds value: {bounds}")
+
+if not isinstance(bounds, tuple):
+    print(f"FAIL: bounds should be tuple, got {type(bounds)}")
+    sys.exit(1)
+
+if len(bounds) != 2:
+    print(f"FAIL: bounds should have 2 elements, got {len(bounds)}")
+    sys.exit(1)
+
+pos, size = bounds
+print(f"pos type: {type(pos)}, value: {pos}")
+print(f"size type: {type(size)}, value: {size}")
+
+if not hasattr(pos, 'x'):
+    print(f"FAIL: pos should be Vector (has no .x), got {type(pos)}")
+    sys.exit(1)
+
+print(f"pos.x={pos.x}, pos.y={pos.y}")
+print(f"size.x={size.x}, size.y={size.y}")
+
+# Test get_bounds() method is removed (#185)
+if hasattr(frame, 'get_bounds'):
+    print("FAIL: get_bounds() method should be removed")
+    sys.exit(1)
+else:
+    print("PASS: get_bounds() method is removed")
+
+print("PASS: Frame bounds test passed!")
+sys.exit(0)