Remove superseded configuration loaders and consolidate runtime tests

internal/domain/domain.go

@@ -192,26 +192,11 @@ type BackendCapacityPolicy struct {
 	QueueCapacity    int
 }
 
-// ExecutionProfile describes how and where to execute a model.
+// ExecutionProfile holds a captured configuration target for execution.
 type ExecutionProfile struct {
-	ID              string         `yaml:"id"`
-	BaseProfileID   string         `yaml:"base_profile"`
-	BackendID       string         `yaml:"backend"`
-	Endpoint        string         `yaml:"endpoint"`
-	Model           string         `yaml:"model"`
-	Temperature     float64        `yaml:"temperature"`
-	MaxTokens       int            `yaml:"max_tokens"`
-	TopP            float64        `yaml:"top_p"`
-	TimeoutSeconds  int            `yaml:"timeout_seconds"`
-	ServiceTier     string         `yaml:"service_tier"`
-	ReasoningEffort string         `yaml:"reasoning_effort"`
-	APIKeyEnv       string         `yaml:"api_key_env"`
-	APIKeyRequired  bool           `yaml:"-" json:"-"`
-	ExtraParams     map[string]any `yaml:"extra_params"`
-	// ResolvedTarget is an execution-owned snapshot assembled from effective
-	// configuration and backend defaults. Legacy source repositories leave it nil.
-	ResolvedTarget *ExecutionTarget        `yaml:"-" json:"-"`
-	TargetPresence ExecutionTargetPresence `yaml:"-" json:"-"`
+	ID             string
+	ResolvedTarget *ExecutionTarget
+	TargetPresence ExecutionTargetPresence
 }
 
 // ExecutionTargetOverride represents per-request runtime setting overrides.