🔍 feat(bdd): add state tracer for debugging test execution and state pollution

- Add STATE_TRACER_README.md documenting purpose, usage, limitations, and future enhancements
- Add state_tracer.go with per-process file-based tracing to $TMPDIR
- Trace scenario start/end, database cleanup, JWT secret operations
- Integrate tracing into suite.go BeforeScenario/AfterScenario hooks
- Document findings: sequential execution per feature, shared database across processes
- Identify root causes: in-memory JWT secrets not isolated by schema, config reload timing

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

pkg/bdd/testserver/state_tracer.go

@@ -0,0 +1,86 @@
+package testserver
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// TraceStateScenarioStart logs the start of a scenario
+func TraceStateScenarioStart(feature, scenario string) {
+	writeTraceLine(feature, scenario, "SCENARIO_START", "")
+}
+
+// TraceStateScenarioEnd logs the end of a scenario
+func TraceStateScenarioEnd(feature, scenario string, err error) {
+	status := "PASSED"
+	if err != nil {
+		status = fmt.Sprintf("FAILED: %v", err)
+	}
+	writeTraceLine(feature, scenario, "SCENARIO_END", status)
+}
+
+// TraceStateDBCleanup logs a database cleanup operation
+func TraceStateDBCleanup(feature, scenario, table string) {
+	writeTraceLine(feature, scenario, "DB_CLEANUP", table)
+}
+
+// TraceStateJWTSecretOperation logs a JWT secret operation
+func TraceStateJWTSecretOperation(feature, scenario, operation, details string) {
+	writeTraceLine(feature, scenario, "JWT_"+operation, details)
+}
+
+// TraceStateSchemaIsolation logs a schema isolation operation
+func TraceStateSchemaIsolation(feature, scenario, operation, details string) {
+	writeTraceLine(feature, scenario, "SCHEMA_"+operation, details)
+}
+
+// TraceStateTransaction logs a transaction boundary
+func TraceStateTransaction(feature, scenario, action, details string) {
+	writeTraceLine(feature, scenario, "TX_"+action, details)
+}
+
+// TraceStateDBRead logs a database read operation
+func TraceStateDBRead(feature, scenario, table, details string) {
+	writeTraceLine(feature, scenario, "DB_SELECT", fmt.Sprintf("table=%s %s", table, details))
+}
+
+// StateTracingEnabled returns true if BDD_TRACE_STATE environment variable is set to "1"
+func StateTracingEnabled() bool {
+	return os.Getenv("BDD_TRACE_STATE") == "1"
+}
+
+// writeTraceLine writes a trace line to the state trace file in $TMPDIR
+func writeTraceLine(feature, scenario, action, details string) {
+	if !StateTracingEnabled() {
+		return
+	}
+	tmpDir := os.Getenv("TMPDIR")
+	if tmpDir == "" {
+		tmpDir = "/tmp"
+	}
+	timestamp := time.Now().Format("20060102-150405")
+	pid := os.Getpid()
+	filename := fmt.Sprintf("bdd-state-trace-%s-%d.log", timestamp, pid)
+	filePath := filepath.Join(tmpDir, filename)
+
+	line := fmt.Sprintf("%s | %-15s | %-40s | %-16s | %s\n",
+		time.Now().Format("2006-01-02T15:04:05.000000"),
+		feature,
+		scenario,
+		action,
+		details,
+	)
+
+	file, err := os.OpenFile(filePath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
+	if err != nil {
+		return
+	}
+	defer file.Close()
+
+	if _, err := file.WriteString(line); err != nil {
+		return
+	}
+	file.Sync()
+}