dispatch: allow empty route kinds (match all) + add routing tests

- config: permit routes[].kinds to be omitted/empty; treat as "all kinds"
- dispatch: compile empty kinds to Route{Kinds:nil} (match all kinds)
- tests: add coverage for route compilation + config validation edge cases

Files:
- config/load.go
- config/config.go
- dispatch/routes.go
- config/validate_test.go
- dispatch/routes_test.go

config/load.go

@@ -133,16 +133,12 @@ func (c *Config) Validate() error {
 			m.Add(fieldErr(path+".sink", fmt.Sprintf("references unknown sink %q (define it under sinks:)", r.Sink)))
 		}
 
-		if len(r.Kinds) == 0 {
-			// You could relax this later (e.g. empty == "all kinds"), but for now
-			// keeping it strict prevents accidental "route does nothing".
-			m.Add(fieldErr(path+".kinds", "must contain at least one kind"))
-		} else {
-			for j, k := range r.Kinds {
-				kpath := fmt.Sprintf("%s.kinds[%d]", path, j)
-				if strings.TrimSpace(k) == "" {
-					m.Add(fieldErr(kpath, "kind cannot be empty"))
-				}
+		// Kinds is optional. If omitted or empty, the route matches ALL kinds.
+		// If provided, each entry must be non-empty.
+		for j, k := range r.Kinds {
+			kpath := fmt.Sprintf("%s.kinds[%d]", path, j)
+			if strings.TrimSpace(k) == "" {
+				m.Add(fieldErr(kpath, "kind cannot be empty"))
 			}
 		}
 	}