Implement spider functionality for event synchronization

- Introduced a new `spider` package to manage connections to admin relays and synchronize events for followed pubkeys.
- Added configuration options for spider mode in the application settings, allowing for different operational modes (e.g., follows).
- Implemented callback mechanisms to dynamically retrieve admin relays and follow lists.
- Enhanced the main application to initialize and manage the spider, including starting and stopping its operation.
- Added tests to validate spider creation, callbacks, and operational behavior.
- Bumped version to v0.17.14.

app/config/config.go

@@ -59,6 +59,9 @@ type C struct {
 	// Sprocket settings
 	SprocketEnabled bool `env:"ORLY_SPROCKET_ENABLED" default:"false" usage:"enable sprocket event processing plugin system"`
 
+	// Spider settings
+	SpiderMode string `env:"ORLY_SPIDER_MODE" default:"none" usage:"spider mode for syncing events: none, follows"`
+
 	PolicyEnabled bool `env:"ORLY_POLICY_ENABLED" default:"false" usage:"enable policy-based event processing (configuration found in $HOME/.config/ORLY/policy.json)"`
 }