fix: align cache controls with config

Remove unused head-check config, make TTL overrides explicit, and tighten revalidation to avoid stale cache behavior.

internal/hubmodule/strategy.go

@@ -11,13 +11,14 @@ type StrategyOptions struct {
 // ResolveStrategy 将模块的默认策略与 hub 级覆盖合并。
 func ResolveStrategy(meta ModuleMetadata, opts StrategyOptions) CacheStrategyProfile {
 	strategy := meta.CacheStrategy
-	if strategy.TTLHint > 0 && opts.TTLOverride > 0 {
-		strategy.TTLHint = opts.TTLOverride
-	}
 	if opts.ValidationOverride != "" {
 		strategy.ValidationMode = opts.ValidationOverride
 	}
-	return normalizeStrategy(strategy)
+	strategy = normalizeStrategy(strategy)
+	if opts.TTLOverride > 0 {
+		strategy.TTLHint = opts.TTLOverride
+	}
+	return strategy
 }
 
 func normalizeStrategy(profile CacheStrategyProfile) CacheStrategyProfile {