Fix verify-pass code bugs #317/#318/#319

Three small bugs surfaced by the #314 docstring-accuracy verify pass:

#317 automation.scroll() dropped the x of its position argument: scroll()
resolved (x, y) but called injectMouseEvent(MouseWheelScrolled, clicks, y),
passing the scroll amount as x. injectMouseEvent now takes the scroll delta as
its own parameter and scroll() forwards the real x/y.

#318 GridView.texture always returned None (a TODO stub). It now returns a
Texture wrapper sharing the underlying shared_ptr<PyTexture>, mirroring
Grid.texture. (mcrfpy.Grid and mcrfpy.GridView are the same type post-#252, so
this fixes both names.)

#319 Entity.visible_entities(radius=None) raised TypeError: radius was parsed
with the 'i' format code, which rejects None. It now parses radius as an object
and treats None / omitted / -1 as "use the grid's default fov_radius"; a
non-int, non-None radius raises a clear TypeError.

- regression tests for each under tests/regression/
- api_surface snapshot re-baselined (visible_entities signature; texture
  property now Texture | None) and docs/stubs regenerated; frozen docstring
  gate still 100%

closes #317
closes #318
closes #319

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KnywUddaFRhkxo5kijxJnv

tests/regression/issue_317_scroll_position_test.py

@@ -0,0 +1,68 @@
+"""
+Regression test for issue #317 -- automation.scroll() ignored the x-coordinate
+of its position argument.
+
+Root cause: scroll() resolved (x, y) from pos but called
+    injectMouseEvent(MouseWheelScrolled, clicks, y)
+passing `clicks` as the x argument, so the resolved x was dropped AND the event's
+mouseWheelScroll.x was set to the scroll amount. The fix gives the scroll delta
+its own injectMouseEvent parameter and forwards the real x/y.
+
+LIMITATION: no Python-observable handler currently consumes a scroll event's
+position (GameEngine maps only the wheel *delta* to a wheel_up/wheel_down action),
+so this test cannot assert the forwarded x end-to-end. It is therefore a smoke /
+API-contract regression guard: scroll(clicks, pos=(x, y)) must accept any x, all
+documented pos forms, and not raise after the injectMouseEvent refactor (which is
+the part that changed how the scroll delta is passed). The x-forwarding itself is
+verified by code inspection (McRFPy_Automation.cpp scroll/injectMouseEvent).
+
+ASCII-only. Prints PASS/FAIL + exit.
+"""
+
+import mcrfpy
+from mcrfpy import automation
+import sys
+
+failures = []
+
+
+def check(label, fn):
+    try:
+        fn()
+        ok = True
+    except Exception as e:
+        ok = False
+        label = "%s (raised %s: %s)" % (label, type(e).__name__, e)
+    if not ok:
+        failures.append(label)
+    print(("  ok  " if ok else " FAIL ") + label)
+
+
+# A scene must be current for event injection to have a target.
+scene = mcrfpy.Scene("issue317")
+mcrfpy.current_scene = scene
+
+# Vary x across the position argument; previously x was silently dropped.
+check("scroll(3) no position", lambda: automation.scroll(3))
+check("scroll(3, pos=None)", lambda: automation.scroll(3, pos=None))
+check("scroll(3, (100, 50)) tuple x!=0", lambda: automation.scroll(3, (100, 50)))
+check("scroll(-2, (0, 50)) x==0", lambda: automation.scroll(-2, (0, 50)))
+check("scroll(1, [250, 75]) list", lambda: automation.scroll(1, [250, 75]))
+check("scroll(5, pos=(640, 480)) keyword", lambda: automation.scroll(5, pos=(640, 480)))
+check("scroll(-5, mcrfpy.Vector(12, 34)) Vector",
+      lambda: automation.scroll(-5, mcrfpy.Vector(12, 34)))
+
+# Same y, different x must both be accepted (the regression dropped x entirely).
+check("scroll(2, (10, 200))", lambda: automation.scroll(2, (10, 200)))
+check("scroll(2, (900, 200))", lambda: automation.scroll(2, (900, 200)))
+
+
+print("")
+if failures:
+    print("FAIL -- %d check(s) failed:" % len(failures))
+    for f in failures:
+        print("  - " + f)
+    sys.exit(1)
+print("PASS -- automation.scroll accepts a full (x, y) position across all forms "
+      "(x-forwarding verified by code inspection; no observable consumer yet).")
+sys.exit(0)