feat(cache,worker): overhaul cache layer and add generation task lease recovery

- shared/cache: add Options/L1/async/metrics/prefix decorators, multi-key ops, Redis pool tuning, and JSON readthrough metrics
- worker-generate: claim tasks via DB lease + heartbeat, requeue stale queued tasks, expire dead leases with refund/cache invalidation
- tenant: version article cache keys so worker recovery invalidations propagate cleanly
- shared/config: expand Redis (pool/timeouts/TLS) and Generation (lease/recovery) configs with defaults

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/ops/app/kol_subscription_cache_test.go

@@ -18,15 +18,28 @@ func (c *recordingCache) Get(context.Context, string) ([]byte, error) {
 	return nil, sharedcache.ErrNotFound
 }
 
+func (c *recordingCache) GetMulti(context.Context, []string) (map[string][]byte, error) {
+	return map[string][]byte{}, nil
+}
+
 func (c *recordingCache) Set(context.Context, string, []byte, time.Duration) error {
 	return nil
 }
 
+func (c *recordingCache) SetMulti(context.Context, []sharedcache.Item) error {
+	return nil
+}
+
 func (c *recordingCache) Delete(_ context.Context, key string) error {
 	c.deletedKeys = append(c.deletedKeys, key)
 	return nil
 }
 
+func (c *recordingCache) DeleteMany(_ context.Context, keys []string) error {
+	c.deletedKeys = append(c.deletedKeys, keys...)
+	return nil
+}
+
 func (c *recordingCache) DeletePrefix(_ context.Context, prefix string) error {
 	c.deletedPrefixes = append(c.deletedPrefixes, prefix)
 	return nil

server/internal/ops/config/config.go

@@ -272,6 +272,7 @@ func load(path string) (*Config, error) {
 	if err := resolved.Scan(&settings); err != nil {
 		return nil, fmt.Errorf("scan config: %w", err)
 	}
+	applySharedDefaults(settings)
 
 	var cfg Config
 	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
@@ -303,6 +304,25 @@ func load(path string) (*Config, error) {
 	return &cfg, nil
 }
 
+func applySharedDefaults(settings map[string]any) {
+	cacheSettings := ensureMapSetting(settings, "cache")
+	if _, ok := cacheSettings["metrics_enabled"]; !ok {
+		cacheSettings["metrics_enabled"] = true
+	}
+}
+
+func ensureMapSetting(settings map[string]any, key string) map[string]any {
+	if settings == nil {
+		return map[string]any{}
+	}
+	if existing, ok := settings[key].(map[string]any); ok {
+		return existing
+	}
+	next := make(map[string]any)
+	settings[key] = next
+	return next
+}
+
 func normalizeConfig(cfg *Config) {
 	if cfg.Server.Port == 0 {
 		cfg.Server.Port = 8090
@@ -313,9 +333,11 @@ func normalizeConfig(cfg *Config) {
 	if strings.TrimSpace(cfg.Redis.Addr) == "" {
 		cfg.Redis.Addr = "localhost:6379"
 	}
+	sharedconfig.NormalizeRedisConfig(&cfg.Redis)
 	if strings.TrimSpace(cfg.Cache.Driver) == "" {
 		cfg.Cache.Driver = "redis"
 	}
+	sharedconfig.NormalizeCacheConfig(&cfg.Cache)
 	if strings.TrimSpace(cfg.Log.Level) == "" {
 		cfg.Log.Level = "info"
 	}