[sturimcode]

macOS 27 compatibility, a recoverable updater and Python 3.15 support.

• Raised the curl_cffi floor from 0.15.0 to 0.17.0. On macOS 27 arm64, 0.15.0 and 0.16.3 fail to import because their wheels do not link CoreFoundation and SystemConfiguration (macOS 27: import curl_cffi fails with "symbol not found in flat namespace '_CFArrayAppendValue'" — wheel does not link CoreFoundation / SystemConfiguration lexiforest/curl_cffi#885), breaking Garmin login. Version 0.17.0 fixes the links, bundles Brotli 1.2.1 and removes a compromised eMudhra certificate from certifi.
• eufy-sync --update no longer imports garminconnect or curl_cffi, so either package can be broken without blocking the command that installs the fix. GarminAuth now loads on first use and doctor loads only for --doctor. A fresh-interpreter test verifies the upgrade runs without attempting either import.
• Added Python 3.15 to the classifiers and the Ubuntu, macOS and Windows CI matrix, bringing it to 12 test legs. curl_cffi 0.17.0 provides Python 3.15 wheels.
• Checked the Cloudflare-block fallback against 0.17.0 on a local server. GET requests, multipart FIT uploads and block-page detection behave as before, so no code change was needed. Multipart part failures now raise an error instead of sending a short body; the fallback already closes the body and passes the error through.
• Updated the version to 1.15.1 in pyproject.toml and eufy_sync/__init__.py.

766 tests pass locally with curl_cffi 0.17.0; ruff is clean.