Adopts the three SDK families convention from
fai/platform/docs/architecture/sdks.md — base name carries
the family, language suffix on dir + repo only:
fai_dart_sdk (pkg) → fai_client_sdk
fai_dart_sdk (dir) → fai_client_sdk_dart
fai/dart-sdk (repo) → fai/client-sdk-dart
Internal lib/test/example file renames track the package
name. Old git.flemming.ws URL also retired here.
Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>
