sud: fail fast on malformed sud.json documents, one test per fixture

Sud.load() now calls utils/sud_validate.py's validate_sud() before
parsing: requires a non-empty 'steps' list, and for every resolved
step that sets its own 'temperature', a numeric ramp.rate - the one
genuinely unguarded crash site (ramp['rate'], no .get() fallback) hit
in tasks/sud.py, components/sud_forecast.py and demo_sud.py the moment
that step is reached, which for SudForecastEstimator can be as early
as the Load itself. A refused load is now logged with the specific
reason (previously silent). validate_sud() reuses Sud._parse_data()
directly rather than reimplementing default-merging/step-building.

tests/utils/test_sud_validate_fixtures.py covers 8 fixture docs plus
all 6 real sude/*.json files; tests/components/sud/test_sud_load.py
exercises the Sud.load() wiring itself (rejects, keeps prior schedule).

Also reworked both this and test_config_fixtures.py to generate one
dedicated test method per fixture file (dynamic setattr) instead of
looping with subTest inside a single method - subTest iterations don't
show up individually in `unittest -v`/IDE test runners, which made it
look like far fewer fixtures were covered than actually are.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F4oEE99rkKVU8L8tkzXWdG

tests/utils/test_config_fixtures.py

@@ -1,5 +1,6 @@
 import json
 import os
+import re
 import unittest
 
 from utils.config_validate import ConfigError, validate_temp_ctrl
@@ -27,20 +28,33 @@ def _load(name):
         return json.load(f)
 
 
+def _test_name(filename):
+    return 'test_' + re.sub(r'\W', '_', filename[:-len('.json')])
+
+
 class TestConfigFixtures(unittest.TestCase):
     def test_every_fixture_file_is_covered(self):
         on_disk = {f for f in os.listdir(FIXTURES_DIR) if f.endswith('.json')}
         self.assertEqual(on_disk, set(CASES), "fixtures/ and CASES have drifted apart")
 
-    def test_fixtures_match_expected_outcome(self):
-        for name, expected_error in CASES.items():
-            with self.subTest(fixture=name):
-                config = _load(name)
-                if expected_error is None:
-                    validate_temp_ctrl(config)  # must not raise
-                else:
-                    with self.assertRaisesRegex(ConfigError, expected_error):
-                        validate_temp_ctrl(config)
+
+def _make_fixture_test(name, expected_error):
+    def test(self):
+        config = _load(name)
+        if expected_error is None:
+            validate_temp_ctrl(config)  # must not raise
+        else:
+            with self.assertRaisesRegex(ConfigError, expected_error):
+                validate_temp_ctrl(config)
+    return test
+
+
+# One dedicated test method per fixture file - not a single method looping
+# over CASES with subTest - so `unittest discover -v` (and any IDE test
+# runner) lists and can re-run each fixture individually instead of folding
+# them all into one opaque "did any of these fail" result.
+for _name, _expected_error in CASES.items():
+    setattr(TestConfigFixtures, _test_name(_name), _make_fixture_test(_name, _expected_error))
 
 
 if __name__ == '__main__':