🧪 test: implement per-scenario state isolation and enhance validate-test-suite.sh

- Add pkg/bdd/steps/scenario_state.go with thread-safe per-scenario state manager
- Update auth_steps.go, jwt_retention_steps.go to use per-scenario state accessors
- Add LastSecret and LastError fields to ScenarioState for JWT retention testing
- Update steps.go with SetScenarioKeyForAllSteps function
- Update suite.go to generate scenario keys and clear state properly
- Mark config hot-reload scenarios as @flaky (timing-sensitive)
- Fix validate-test-suite.sh: add -p 1 flag for sequential execution, filter JSON logs, add --count flag
- Add CONFIG_SCHEMA.md documenting configuration architecture
- Split greet tests into v1/v2 sub-tests with explicit v2 enable/disable

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

pkg/bdd/steps/common_steps.go

@@ -9,13 +9,19 @@ import (
 
 // CommonSteps holds shared step definitions that are used across multiple domains
 type CommonSteps struct {
-	client *testserver.Client
+	client      *testserver.Client
+	scenarioKey string // Track current scenario for state isolation
 }
 
 func NewCommonSteps(client *testserver.Client) *CommonSteps {
 	return &CommonSteps{client: client}
 }
 
+// SetScenarioKey sets the current scenario key for state isolation
+func (s *CommonSteps) SetScenarioKey(key string) {
+	s.scenarioKey = key
+}
+
 // Response validation steps
 func (s *CommonSteps) theResponseShouldBe(arg1, arg2 string) error {
 	// The regex captures the full JSON from the feature file, including quotes