fix(server): per-org settings and ESO read token

The settings collection was a single global document, so every org
shared one SMTP config, alert config, retention policy and ESO read
token. GetSecretGroupDecryptedAny then flattened every org's secrets
for a group into one map, meaning any tenant's token read every
tenant's secrets.

- settings gains org_id; GetSettings/SaveSettings/RotateSecretsReadToken/
  GetWorkflowLogRetentionDays all take orgID
- VerifySecretsReadToken replaced by ResolveSecretsReadToken, which
  resolves the org from the presented token's hash; the ESO endpoint
  derives its org from the token rather than a session, since it is
  called machine-to-machine
- GetSecretGroupDecryptedAny deleted in favour of the org-scoped variant
- settings and token-rotation routes now require owner/admin
- offline sweep and log retention resolve org per server / per run
- migration 0002 stamps the legacy settings doc with the default org

Note: /api/settings now 403s for members; the web settings page needs a
matching role check.

server/internal/api/handlers.go

@@ -59,9 +59,13 @@ func RegisterRoutes(r *gin.Engine) {
 
 		apiGroup.GET("/audit", listAuditEvents)
 
-		apiGroup.GET("/settings", getSettings)
-		apiGroup.PUT("/settings", saveSettings)
-		apiGroup.POST("/settings/secrets-token", rotateSecretsToken)
+		settings := apiGroup.Group("/settings")
+		settings.Use(auth.RequireRole("owner", "admin"))
+		{
+			settings.GET("", getSettings)
+			settings.PUT("", saveSettings)
+			settings.POST("/secrets-token", rotateSecretsToken)
+		}
 
 		apiGroup.GET("/secrets", listSecretGroups)
 		apiGroup.POST("/secrets", createSecretGroup)
@@ -456,7 +460,7 @@ func listAuditEvents(c *gin.Context) {
 }
 
 func getSettings(c *gin.Context) {
-	s, err := services.GetSettings()
+	s, err := services.GetSettings(auth.OrgID(c))
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
@@ -474,7 +478,7 @@ func saveSettings(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
-	if err := services.SaveSettings(body.Alerts, body.Email, body.WorkflowLogRetentionDays); err != nil {
+	if err := services.SaveSettings(auth.OrgID(c), body.Alerts, body.Email, body.WorkflowLogRetentionDays); err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}

server/internal/api/secrets.go

@@ -19,19 +19,29 @@ func validName(s string) bool {
 	return s != "" && len(s) <= 128 && groupNamePattern.MatchString(s)
 }
 
-// secretsReadAuth validates the ESO bearer token on the public read endpoint.
+// ctxSecretsOrgKey carries the org resolved from the ESO bearer token.
+const ctxSecretsOrgKey = "km_secrets_org"
+
+// secretsReadAuth validates the ESO bearer token on the public read endpoint
+// and stashes the org the token belongs to.
+//
+// This is the one endpoint whose org does NOT come from the session or the
+// host: External Secrets Operator calls it machine-to-machine with no session,
+// so the token itself is the org-bearing credential.
 func secretsReadAuth() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		const prefix = "Bearer "
-		auth := c.GetHeader("Authorization")
-		if len(auth) <= len(prefix) || !strings.EqualFold(auth[:len(prefix)], prefix) {
+		authHeader := c.GetHeader("Authorization")
+		if len(authHeader) <= len(prefix) || !strings.EqualFold(authHeader[:len(prefix)], prefix) {
 			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing bearer token"})
 			return
 		}
-		if !services.VerifySecretsReadToken(auth[len(prefix):]) {
+		orgID, ok := services.ResolveSecretsReadToken(authHeader[len(prefix):])
+		if !ok {
 			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
 			return
 		}
+		c.Set(ctxSecretsOrgKey, orgID)
 		c.Next()
 	}
 }
@@ -41,7 +51,9 @@ func secretsReadAuth() gin.HandlerFunc {
 // (ESO treats 404 as "deleted").
 func esoGetGroup(c *gin.Context) {
 	group := c.Param("group")
-	values, err := services.GetSecretGroupDecryptedAny(group)
+	// Org comes from the bearer token (set by secretsReadAuth), not a session.
+	orgID := c.GetString(ctxSecretsOrgKey)
+	values, err := services.GetSecretGroupDecrypted(orgID, group)
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "store error"})
 		return
@@ -179,7 +191,7 @@ func deleteSecretGroup(c *gin.Context) {
 }
 
 func rotateSecretsToken(c *gin.Context) {
-	token, err := services.RotateSecretsReadToken()
+	token, err := services.RotateSecretsReadToken(auth.OrgID(c))
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return