Assorted compiler warnings cleanup

Cleans up a bunch of compiler & static analysis warnings from gcc 14.1:

• LocalInitTransports: Fix -Wuseless-cast warning for getenv() call
• SocketCreateListener: Fix -Wuseless-cast warning in bind() call
• Clear numerous -Wsign-compare warnings from gcc 14.1
• SocketINETConnect: return failure when malloc() fails
• ParseAddress: return failure when strdup() fails
• MakeAllCOTSServerListeners: Initialize temp_ciptrs
• GetMyNetworkId: Avoid writing to NULL pointer if malloc() fails
• GetPeerNetworkId: Avoid writing to NULL pointer if malloc() fails
• GetPeerNetworkId: avoid calling strlen() on a NULL pointer
• SocketOpen: avoid leak of out-of-range fd
• is_numeric: Add TRANS_SERVER to required ifdefs