Enhance logging and timing in CLI and session operations

- Updated the `_print_checks` function to replace console prints with logging functions for better traceability.
- Introduced timing functionality in the `doctor`, `dry_run`, and `up` functions to log the duration of preflight checks.
- Modified the `wait_ssh` function to accept a logging callback, improving SSH wait feedback.
- Enhanced the `mark` method in `PhaseTimes` to log phase durations, aiding in performance analysis.
- Updated various remote scripts to ensure error messages are printed to stderr for better error handling.

src/gpu_rent/remote/bootstrap.sh

@@ -9,7 +9,7 @@ MARKER_DATA="${DATA_ROOT}/.gpu-rent-ready"
 MARKER_BOOT="${SWARM_ROOT}/.gpu-rent-bootstrapped"
 SWARM_REPO="https://github.com/mcmonkeyprojects/SwarmUI.git"
 
-log() { echo "[gpu-rent] $*"; }
+log() { echo "[gpu-rent] $*" >&2; }
 
 if [[ "$(id -u)" -ne 0 ]]; then
   echo "нужен root (sudo -n bash $0)" >&2