feat(tak): phase 3 multicast SA support

[krital]

Summary

• add optional UDP multicast transport for TAK situational awareness traffic
• gate multicast behavior via TAK extension config (multicast_enabled, ingress/egress toggles, group/port/interface/ttl)
• integrate multicast lifecycle into TakExtension (startup, shutdown, ingress read loop, best-effort outbound send)
• keep existing TCP/TLS stream path unchanged as primary transport

Config Added

• multicast_enabled (default: false)
• multicast_ingress_enabled (default: follows multicast_enabled)
• multicast_egress_enabled (default: follows multicast_enabled)
• multicast_group (default: 239.2.3.1)
• multicast_port (default: 6969)
• multicast_interface (optional interface name or address)
• multicast_ttl (default: 1)
• multicast_read_buffer_bytes (default: 8192)

Validation

• JAVA_HOME=$HOME/.sdkman/candidates/java/21.0.9-zulu mvn -q -Dtest=io.mapsmessaging.network.protocol.impl.tak.TakExtensionTest,io.mapsmessaging.network.protocol.impl.tak.codec.CotXmlCodecTest,io.mapsmessaging.network.protocol.impl.tak.codec.TakProtobufCodecTest,io.mapsmessaging.network.protocol.impl.tak.framing.TakStreamFramerTest,io.mapsmessaging.network.protocol.impl.tak.framing.TakStreamFramerXmlTest test
• JAVA_HOME=$HOME/.sdkman/candidates/java/21.0.9-zulu mvn -q -Dmaven.test.skip=true package

Notes

• Phase 1 PR: feat(tak): add phase 1 TAK extension integration #2056
• Phase 2 PR: feat(tak): phase 2 protobuf support #2057
• This PR contains Phase 3 incremental changes on top of Phase 2 branch history.

[krital]

Superseded by consolidated TAK PR #2061 (codex/feat-tak). Closing phase PR to keep review in one place.