Restructure refimpl into go-lang and python subdirectories

Move Go reference implementation to refimpl/go-lang/ and add new
Python reference implementation in refimpl/python/. Update build.sh
with renamed draft and simplified tool paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

refimpl/python/tests/test_config.py

@@ -0,0 +1,49 @@
+"""Tests for config module."""
+
+import os
+
+import pytest
+
+from ect import default_config, load_config_from_env
+from ect.config import ENV_IAT_MAX_AGE_MINUTES, ENV_JTI_REPLAY_CACHE_SIZE
+
+
+def test_default_config():
+    c = default_config()
+    assert c.iat_max_age_sec == 900
+    assert c.jti_replay_size == 0
+
+
+def test_load_config_from_env():
+    os.environ[ENV_IAT_MAX_AGE_MINUTES] = "20"
+    os.environ[ENV_JTI_REPLAY_CACHE_SIZE] = "500"
+    try:
+        c = load_config_from_env()
+        assert c.iat_max_age_sec == 20 * 60
+        assert c.jti_replay_size == 500
+    finally:
+        os.environ.pop(ENV_IAT_MAX_AGE_MINUTES, None)
+        os.environ.pop(ENV_JTI_REPLAY_CACHE_SIZE, None)
+
+
+def test_config_create_options():
+    c = default_config()
+    opts = c.create_options("my-kid")
+    assert opts.key_id == "my-kid"
+    assert opts.default_expiry_sec == c.default_expiry_sec
+
+
+def test_config_verify_options():
+    c = default_config()
+    opts = c.verify_options()
+    assert opts.iat_max_age_sec == c.iat_max_age_sec
+    assert opts.dag is not None
+
+
+def test_load_config_invalid_int():
+    os.environ[ENV_IAT_MAX_AGE_MINUTES] = "bad"
+    try:
+        c = load_config_from_env()
+        assert c.iat_max_age_sec == 900
+    finally:
+        os.environ.pop(ENV_IAT_MAX_AGE_MINUTES, None)