Add godoc documentation and README with code structure

Add comprehensive godoc comments to all exported types, functions,
and constants throughout the codebase. Create README.md documenting
the project architecture, execution flow, database schema, and
component relationships.

internal/routewatch/peerhandler.go

@@ -74,13 +74,18 @@ func (h *PeerHandler) WantsMessage(_ string) bool {
 	return true
 }
 
-// QueueCapacity returns the desired queue capacity for this handler
+// QueueCapacity returns the desired queue capacity for this handler.
+// The PeerHandler uses a large queue capacity because batching allows
+// for efficient processing of many updates at once.
 func (h *PeerHandler) QueueCapacity() int {
 	// Batching allows us to use a larger queue
 	return peerHandlerQueueSize
 }
 
-// HandleMessage processes a message to track peer information
+// HandleMessage processes a RIS message to track peer information.
+// It extracts the peer IP address and ASN from the message and adds
+// the update to an internal batch. When the batch reaches peerBatchSize
+// or the batch timeout expires, the batch is flushed to the database.
 func (h *PeerHandler) HandleMessage(msg *ristypes.RISMessage) {
 	// Parse peer ASN from string
 	peerASN := 0