add value-shape field classification and auto-apply

Field roles are now inferred from observed values instead of names,
with src/dst disambiguation, value-pattern detector hints, an Ollama
advisor scoped to ambiguous fields only, confidence-gated auto-apply
with manual-field protection, and drift flagging for review

tests/test_entities.py

@@ -0,0 +1,21 @@
+import unittest
+
+from fgai.entities import is_public_ip
+
+
+class EntitiesTests(unittest.TestCase):
+    def test_is_public_ip_true_for_global_address(self):
+        self.assertTrue(is_public_ip("8.8.8.8"))
+
+    def test_is_public_ip_false_for_private_address(self):
+        self.assertFalse(is_public_ip("10.0.0.5"))
+        self.assertFalse(is_public_ip("192.168.1.1"))
+
+    def test_is_public_ip_false_for_invalid_value(self):
+        self.assertFalse(is_public_ip("not-an-ip"))
+        self.assertFalse(is_public_ip(""))
+        self.assertFalse(is_public_ip(None))
+
+
+if __name__ == "__main__":
+    unittest.main()