Move Kimi, Grok, and Qwen onto managed_runtime.go and shell_command.go;
share the encoded and shell command builders and the quoted Windows
legacy parser with Droid; split managed_changes.go; dedupe Letta's hook
entry filtering and stop swallowing settings read errors.
Claude-Session: https://claude.ai/code/session_01Agoc9bRVE9KL7mmWtey9Vq
Move the four providers onto managed_runtime.go and shell_command.go;
keep the Auggie wrappers, Cline metadata wrappers, and the Copilot and
Droid precondition handling provider-local.
Claude-Session: https://claude.ai/code/session_01Agoc9bRVE9KL7mmWtey9Vq