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/sud_fixtures/empty_steps_list.json

@@ -0,0 +1,17 @@
+{
+	"Name": "EmptySteps",
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	},
+	"steps": []
+}

tests/utils/sud_fixtures/missing_ramp_rate.json

@@ -0,0 +1,24 @@
+{
+	"Name": "MissingRampRate",
+	"pot": {
+		"grain_mass": 0,
+		"water_mass": 20
+	},
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"hold": {
+				"duration": 0
+			},
+			"ramp": {}
+		}
+	},
+	"steps": [
+		{
+			"descr": "Heat up",
+			"temperature": 65
+		}
+	]
+}

tests/utils/sud_fixtures/missing_steps_key.json

@@ -0,0 +1,16 @@
+{
+	"Name": "NoSteps",
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	}
+}

tests/utils/sud_fixtures/ramp_rate_wrong_type.json

@@ -0,0 +1,29 @@
+{
+	"Name": "WrongType",
+	"pot": {
+		"grain_mass": 0,
+		"water_mass": 20
+	},
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	},
+	"steps": [
+		{
+			"descr": "Heat up",
+			"temperature": 65,
+			"ramp": {
+				"rate": "fast"
+			}
+		}
+	]
+}

tests/utils/sud_fixtures/step_not_dict.json

@@ -0,0 +1,19 @@
+{
+	"Name": "StepNotDict",
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	},
+	"steps": [
+		"not a step object"
+	]
+}

tests/utils/sud_fixtures/valid_minimal.json

@@ -0,0 +1,25 @@
+{
+	"Name": "Minimal",
+	"pot": {
+		"grain_mass": 0,
+		"water_mass": 20
+	},
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	},
+	"steps": [
+		{
+			"descr": "Only step"
+		}
+	]
+}

tests/utils/sud_fixtures/valid_multi_step.json

@@ -0,0 +1,43 @@
+{
+	"Name": "MultiStep",
+	"pot": {
+		"grain_mass": 0,
+		"water_mass": 22
+	},
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	},
+	"steps": [
+		{
+			"descr": "Aufheizen",
+			"temperature": 57,
+			"ramp": {
+				"rate": 1.5
+			}
+		},
+		{
+			"descr": "Rast",
+			"temperature": 63,
+			"hold": {
+				"duration": 40
+			}
+		},
+		{
+			"descr": "Ausmaischen",
+			"temperature": 78,
+			"ramp": {
+				"rate": 1.0
+			}
+		}
+	]
+}

tests/utils/sud_fixtures/valid_with_target.json

@@ -0,0 +1,32 @@
+{
+	"Name": "WithTarget",
+	"pot": {
+		"grain_mass": 0,
+		"water_mass": 20
+	},
+	"default": {
+		"step": {
+			"descr": "Put description here",
+			"user_wait_for_continue": false,
+			"temperature": 0,
+			"ramp": {
+				"rate": 1.0
+			},
+			"hold": {
+				"duration": 0
+			}
+		}
+	},
+	"steps": [
+		{
+			"descr": "Heat up",
+			"temperature": 65
+		},
+		{
+			"descr": "Hold",
+			"hold": {
+				"duration": 20
+			}
+		}
+	]
+}