docs+scripts: add iOS build and simulator run commands

scripts/build-ios-client.sh: builds VoiceCatiOS.app for iOS simulator
  - calls build-xcframework.sh --all (all 3 slices required for iOS sim slice)
  - xcodebuild -target VoiceCatiOS with SYMROOT=OBJROOT to co-locate SPM
    and app build products (fixes "unable to resolve module dependency" error)
  - stages result to dist/ios-client/

scripts/run-ios-simulator.sh: installs and launches on an iPhone simulator
  - finds a booted simulator or boots the first available iPhone sim
  - opens Simulator.app, installs via simctl install, launches via simctl launch
  - --build flag to build first; --log to stream app logs; --device / --udid to
    pin a specific simulator

scripts/build-all.sh: add --ios-client opt-in flag (macOS only)

docs/building.md:
  - add iOS entry to quick-nav table
  - update §6 (apple platform): remove "scaffolding" caveat now that iOS slices
    are validated; trim to essentials + pointer to build-xcframework.sh
  - add §9 (iOS client SwiftUI): XCFramework, xcodebuild command with rationale
    for -target/-SYMROOT flags, run script usage, full simctl commands, Xcode UI

scripts/build-all.sh

@@ -4,6 +4,7 @@
 # dist/. Convenience wrapper over the per-artifact scripts in scripts/.
 #
 # On macOS:   server + libs (macOS slice + xcframework) + macos-client (.app)
+#             optionally: iOS client for simulator (pass --ios-client)
 # On Windows: server + libs (windows DLL) + windows-client (.exe folder)
 # On Linux:   server only (no native client presets target Linux)
 #
@@ -14,6 +15,7 @@
 #   scripts/build-all.sh --skip-client    # skip the GUI client(s)
 #   scripts/build-all.sh --skip-libs      # skip the library artifacts
 #   scripts/build-all.sh --skip-server    # skip the server
+#   scripts/build-all.sh --ios-client     # also build iOS simulator client (macOS only)
 #   scripts/build-all.sh -h|--help
 set -euo pipefail
 
@@ -25,6 +27,7 @@ PASS_ARGS=()
 SKIP_CLIENT=false
 SKIP_LIBS=false
 SKIP_SERVER=false
+BUILD_IOS_CLIENT=false
 while [[ $# -gt 0 ]]; do
     case "$1" in
         --dist)         PASS_ARGS+=( --dist "$2" ); vc_set_dist "$2"; shift 2 ;;
@@ -32,6 +35,7 @@ while [[ $# -gt 0 ]]; do
         --skip-client)  SKIP_CLIENT=true; shift ;;
         --skip-libs)    SKIP_LIBS=true; shift ;;
         --skip-server)  SKIP_SERVER=true; shift ;;
+        --ios-client)   BUILD_IOS_CLIENT=true; shift ;;
         -h|--help)      vc_print_help "$0"; exit 0 ;;
         *) vc_die "unknown arg: $1 (try --help)" ;;
     esac
@@ -61,6 +65,7 @@ fi
 if ! $SKIP_CLIENT; then
     if [[ "$HOST" == "macos" ]]; then
         run build-macos-client.sh
+        $BUILD_IOS_CLIENT && run build-ios-client.sh
     elif [[ "$HOST" == "windows" ]]; then
         run build-windows-client.sh
     fi