The QBIT_SLACK provider declares its capabilities and returns status, message
id and reasons through core SendMessageOutput; idempotency keys and templates
come from SendMessageInput.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
RC.1-RC.3 failed to start on RC.7: the reflection adapter (written against the
#1162 stand-in) called a withSection signature RC.7 doesn't have. Replace it with
SlackPreferencesProvider on the real SPI (section, connections list, Connect,
Install, test message and Disconnect actions, read-only store), registered only
when the core classes exist. Startup test validates the instance on RC.7.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>