Add context-aware decoding for GET RESPONSE and TERMINAL RESPONSE

decode.py:
- decode_cat: TERMINAL RESPONSE (0x14) now extracts the proactive
  command type from its echoed Command Details (tag 81) — no history
  lookup needed since TR carries its own type
- decode_message gains prev param; GET RESPONSE (0xC0) resolves
  'response_for' from the previous command when its SW1 was 0x61,
  else None (orphaned)
- decode_sniff_msg threads prev through

database.py:
- _row_to_message accepts prev; new _decode_rows tracks previous-TPDU
  context in sequence; get_messages/get_messages_after seed context
  from the message before the window/cursor

tests: TR cat_command + GET RESPONSE context/orphaned cases (49 total)

tests/test_decode.py

@@ -66,11 +66,11 @@ class TestCatDecoding(unittest.TestCase):
         self.assertEqual(r['ins_name'], 'ENVELOPE')
         self.assertEqual(r['cat_command'], 'EVENT DOWNLOAD')
 
-    def test_tr_no_cat(self):
+    def test_tr_has_cat(self):
         r = decode_message(bytes.fromhex(
             '801400000C8103010500020282810301009130'))
         self.assertEqual(r['ins_name'], 'TERMINAL RESPONSE')
-        self.assertNotIn('cat_command', r)
+        self.assertEqual(r['cat_command'], 'SET UP EVENT LIST')
 
     def test_select_no_cat(self):
         r = decode_message(bytes.fromhex('a0a40000023f009000'))
@@ -119,5 +119,39 @@ class TestChangeAndFidiDecoding(unittest.TestCase):
         self.assertEqual(r['di_val'], 64)
 
 
+class TestTerminalResponse(unittest.TestCase):
+    def test_tr_setup_event_list(self):
+        r = decode_message(bytes.fromhex(
+            '801400000C8103010500020282810301009130'))
+        self.assertEqual(r['ins_name'], 'TERMINAL RESPONSE')
+        self.assertEqual(r['cat_command'], 'SET UP EVENT LIST')
+
+    def test_tr_setup_menu(self):
+        r = decode_message(bytes.fromhex(
+            '801400000C810301250002028281830100910F'))
+        self.assertEqual(r['cat_command'], 'SET UP MENU')
+
+    def test_tr_poll_interval(self):
+        r = decode_message(bytes.fromhex(
+            '80140000108103010300020282810301000402011E9000'))
+        self.assertEqual(r['cat_command'], 'POLL INTERVAL')
+
+
+class TestGetResponseContext(unittest.TestCase):
+    GET_RESPONSE = bytes.fromhex('00C000002962278202782183023F00A50A800171')
+
+    def test_with_prev_select(self):
+        r = decode_message(self.GET_RESPONSE, prev={'ins_name': 'SELECT', 'sw1': '61'})
+        self.assertEqual(r['response_for'], 'SELECT')
+
+    def test_with_prev_non_61(self):
+        r = decode_message(self.GET_RESPONSE, prev={'ins_name': 'SELECT', 'sw1': '90'})
+        self.assertIsNone(r['response_for'])
+
+    def test_orphaned(self):
+        r = decode_message(self.GET_RESPONSE, prev=None)
+        self.assertIsNone(r['response_for'])
+
+
 if __name__ == '__main__':
     unittest.main()