Add UART SET_LOG_LEVEL for runtime master ESP-IDF logging.

Expose the command via goTool CLI/REST and dashboard controls so log verbosity can be tuned without reflashing.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/adding-a-feature.md

@@ -345,7 +345,7 @@ idf.py build
 
 Ähnliche Features zum Abgucken:
 
-- **Nur Master, kein ESP-NOW:** `main/cmd/cmd_version.c`, `main/cmd/cmd_led_ring.c`
+- **Nur Master, kein ESP-NOW:** `main/cmd/cmd_version.c`, `main/cmd/cmd_led_ring.c`, `main/cmd/cmd_set_log_level.c`
 - **Nur Slave per ESP-NOW (Master leitet nur durch):** `main/cmd/cmd_espnow_unicast_test.c`
 - **Master + alle Slaves / Filter:** `main/cmd/cmd_accel_deadzone.c`
 - **Großer ESP-NOW-Fluss mit Status:** `ota_espnow.c`, `main/cmd/cmd_ota.c`