Add comprehensive godoc documentation to handler.go

Expand documentation comments for SimpleHandler type and its methods
to better explain their purpose, parameters, and behavior.

internal/database/models.go

@@ -17,7 +17,8 @@ type ASN struct {
 	LastSeen    time.Time `json:"last_seen"`
 }
 
-// Prefix represents an IP prefix (CIDR block)
+// Prefix represents an IP prefix (CIDR block) with its IP version (4 or 6)
+// and first/last seen timestamps.
 type Prefix struct {
 	ID        uuid.UUID `json:"id"`
 	Prefix    string    `json:"prefix"`
@@ -26,7 +27,8 @@ type Prefix struct {
 	LastSeen  time.Time `json:"last_seen"`
 }
 
-// Announcement represents a BGP announcement
+// Announcement represents a BGP announcement or withdrawal event,
+// containing the prefix, AS path, origin ASN, peer ASN, next hop, and timestamp.
 type Announcement struct {
 	ID           uuid.UUID `json:"id"`
 	PrefixID     uuid.UUID `json:"prefix_id"`
@@ -38,7 +40,8 @@ type Announcement struct {
 	IsWithdrawal bool      `json:"is_withdrawal"`
 }
 
-// ASNPeering represents a peering relationship between two ASNs
+// ASNPeering represents a peering relationship between two ASNs,
+// stored with the lower ASN as ASA and the higher as ASB.
 type ASNPeering struct {
 	ID        uuid.UUID `json:"id"`
 	ASA       int       `json:"as_a"`