Add node:test suite for vendored C-APDU parser and SCP80 decryption

frontend/tests/ (otaman-style function extraction from index.html):
- apdu_parse.test.js: PARSE_INS registry, parseOneApdu (SELECT by FID,
  READ BINARY Le-form, UPDATE BINARY, GET DATA, lowercase input),
  parseCompactApdus (concatenated implied-CLA stream, graceful
  unrecognized-byte degradation).
- scp80_decrypt.test.js: decryptSecured known-answer tests with
  node-crypto generated ciphertexts — 3DES-CBC 2/3-key (real CNTR=200
  revealed), AES-CBC 128, single DES, wrong-key padding guard, key
  length validation, unsupported-algorithm rejection.
- helpers.js: brace-matched function/const/section extraction from
  the single-file frontend; package.json ("test": "node --test").

Fix AES-CBC decryption path found by the new tests: SubtleCrypto CBC
decrypt always validates PKCS#7, which SCP80 PCNTR-style padding
violates. Workaround: append a synthetic block C* = E(C_last XOR
padBlock) so the validator sees a full 0x10 padding block, decrypt,
then discard the synthetic plaintext. Validated: CNTR=200 case
decrypts correctly.

Version 1.20.1, SW cache simtrace-analyser-v29.

tests/test_pcap_import.py

@@ -197,7 +197,7 @@ class TestImportEndpoint(unittest.TestCase):
 class TestVersion(unittest.TestCase):
     def test_package_version(self):
         from simtrace2_pysniff import __version__
-        self.assertEqual(__version__, '1.20.0')
+        self.assertEqual(__version__, '1.20.1')
 
     def test_status_includes_version(self):
         import os