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/database/database.go

@@ -1435,7 +1435,7 @@ func (d *Database) GetASDetailsContext(ctx context.Context, asn int) (*ASN, []Li
 	return &asnInfo, allPrefixes, nil
 }
 
-// ASPeer represents a peering relationship with another AS
+// ASPeer represents a peering relationship with another AS including handle, description, and timestamps.
 type ASPeer struct {
 	ASN         int       `json:"asn"`
 	Handle      string    `json:"handle"`