Android AAR builds fixed; unified EgressClient added

Fixes

• Add a unified EgressClient::start_egress that calls the v2 Egress.StartEgress RPC with a StartEgressRequest, alongside the existing per-type helpers.
• Fix the Android AAR build. Two cargo-make bugs kept cargo make --profile release android-package from ever producing a release artifact: the per-arch tasks' env = { TARGET = ... } replaced (rather than merged) the parent env map, dropping the --release flag, and the TARGET they set leaked into the Kotlin bindgen's host build, which then cross-compiled with the host linker. Also raise the Swift and Android size budgets to match the binaries as they stand since the data-track UniFFI surface landed, and check out the released tag rather than the dispatch ref when building the wrapper packages.