Retire legacy SOT compatibility route

sot

@@ -1 +0,0 @@
-.sot

tools/check_s91_cto_dotpath.py

@@ -3,7 +3,6 @@
 
 from __future__ import annotations
 
-import os
 import re
 from pathlib import Path
 
@@ -29,10 +28,8 @@ def main() -> int:
     if not (ROOT / ".sot").is_dir():
         fail("missing canonical .sot directory")
     legacy = ROOT / "sot"
-    if not legacy.is_symlink():
-        fail("legacy sot path must be a temporary symlink")
-    if os.readlink(legacy) != ".sot":
-        fail("legacy sot symlink must target .sot")
+    if legacy.exists() or legacy.is_symlink():
+        fail("legacy sot path must be absent after compatibility retirement")
 
     for relative in REQUIRED_FILES:
         if not (ROOT / relative).is_file():