chore: scaffold Voice iOS app (Phase 0)

XcodeGen project, SwiftUI iOS 17 target dev.shane.voice, SPM
livekit-client-swift 2.16.0, mic usage + ATS LAN exception in
Info.plist, placeholder conversation screen and Settings with
server URL field.

AGENTS.md

@@ -0,0 +1,3 @@
+# AGENTS.md
+
+- If using XcodeBuildMCP, use the installed XcodeBuildMCP skill before calling XcodeBuildMCP tools.