List view: decoded summaries for ATR/PPS/RST/VCC instead of raw hex

- decode.py: decode_sniff_msg builds list summaries — ATR: protocol(s),
  TA1 F/D + ratio, T=15 classes, data rate (when a CLK rate was known);
  PPS: protocol + F/D + ratio; RST: 'CLK x.xxx MHz' when the event
  carried a rate
- index.html: cmd_description returns summary || '' for these types and
  STATUS, never falling back to opaque bytes like 010100
- tests: ATR (plain/TA1/classes+rate/unparsed), PPS, RST CLK/no-CLK, VCC
- Bump 1.22.20, SW cache v51->v52

tests/test_pcap_import.py

@@ -224,7 +224,7 @@ class TestImportEndpoint(unittest.TestCase):
 class TestVersion(unittest.TestCase):
     def test_package_version(self):
         from simtrace2_pysniff import __version__
-        self.assertEqual(__version__, '1.22.19')
+        self.assertEqual(__version__, '1.22.20')
 
     def test_status_includes_version(self):
         import os