Enhance graceful shutdown and logging for HTTP server

- Implemented graceful shutdown for the HTTP server, allowing for a controlled shutdown process with a timeout.
- Added logging for shutdown signals and server exit to improve traceability during application termination.
- Introduced IP blacklist configuration to enhance security by blocking specified IP addresses.
- Updated database cache configurations to allow dynamic adjustment via environment variables for better performance tuning.

app/config/config.go

@@ -31,12 +31,15 @@ type C struct {
 	EnableShutdown      bool          `env:"ORLY_ENABLE_SHUTDOWN" default:"false" usage:"if true, expose /shutdown on the health port to gracefully stop the process (for profiling)"`
 	LogLevel            string        `env:"ORLY_LOG_LEVEL" default:"info" usage:"relay log level: fatal error warn info debug trace"`
 	DBLogLevel          string        `env:"ORLY_DB_LOG_LEVEL" default:"info" usage:"database log level: fatal error warn info debug trace"`
+	DBBlockCacheMB      int           `env:"ORLY_DB_BLOCK_CACHE_MB" default:"512" usage:"Badger block cache size in MB (higher improves read hit ratio)"`
+	DBIndexCacheMB      int           `env:"ORLY_DB_INDEX_CACHE_MB" default:"256" usage:"Badger index cache size in MB (improves index lookup performance)"`
 	LogToStdout         bool          `env:"ORLY_LOG_TO_STDOUT" default:"false" usage:"log to stdout instead of stderr"`
 	Pprof               string        `env:"ORLY_PPROF" usage:"enable pprof in modes: cpu,memory,allocation,heap,block,goroutine,threadcreate,mutex"`
 	PprofPath           string        `env:"ORLY_PPROF_PATH" usage:"optional directory to write pprof profiles into (inside container); default is temporary dir"`
 	PprofHTTP           bool          `env:"ORLY_PPROF_HTTP" default:"false" usage:"if true, expose net/http/pprof on port 6060"`
 	OpenPprofWeb        bool          `env:"ORLY_OPEN_PPROF_WEB" default:"false" usage:"if true, automatically open the pprof web viewer when profiling is enabled"`
 	IPWhitelist         []string      `env:"ORLY_IP_WHITELIST" usage:"comma-separated list of IP addresses to allow access from, matches on prefixes to allow private subnets, eg 10.0.0 = 10.0.0.0/8"`
+	IPBlacklist         []string      `env:"ORLY_IP_BLACKLIST" usage:"comma-separated list of IP addresses to block; matches on prefixes to allow subnets, e.g. 192.168 = 192.168.0.0/16"`
 	Admins              []string      `env:"ORLY_ADMINS" usage:"comma-separated list of admin npubs"`
 	Owners              []string      `env:"ORLY_OWNERS" usage:"comma-separated list of owner npubs, who have full control of the relay for wipe and restart and other functions"`
 	ACLMode             string        `env:"ORLY_ACL_MODE" usage:"ACL mode: follows, managed (nip-86), none" default:"none"`