The iroh xcframework needs more system frameworks than the legacy build: iroh's
netwatch uses Network.framework (nw_* symbols), and the objc2 bindings pull in
CoreFoundation/Foundation/objc/iconv. Add them to OTHER_LDFLAGS so TetherApp
links against the iroh core (verified: arm64 simulator BUILD SUCCEEDED; harmless
extra frameworks for the legacy build too).
Also add examples/iroh_send.rs — a one-shot test sender to pre-flight the agent's
receive path (clipboard write + provenance toast) without a second device.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>