feat(valve): Make end-position current thresholds configurable

Introduces separate Modbus holding registers for configurable end-position
current thresholds for both opening and closing valve movements.

- Added REG_HOLDING_VALVE_END_CURRENT_THRESHOLD_OPEN_MA and
  REG_HOLDING_VALVE_END_CURRENT_THRESHOLD_CLOSE_MA to modbus_server.h.
- Modified valve.c to use these new thresholds and save/load them via settings.
- Added new setter functions to valve.h.
- Created new shell_valve library with commands to set/get these thresholds.
- Updated modbus_tool.py to include new menu options for setting thresholds.
- Updated docs/modbus-registers.de.md to document the new registers.

This enhances the flexibility and calibration of the valve control system.

software/lib/shell_valve/CMakeLists.txt

@@ -0,0 +1 @@
+zephyr_library()

software/lib/shell_valve/Kconfig

@@ -0,0 +1,6 @@
+config SHELL_VALVE
+	bool "Shell Valve commands"
+	default y
+	depends on SHELL
+	help
+	  Enable the shell commands for valve control.

software/lib/shell_valve/shell_valve.c

@@ -0,0 +1,115 @@
+#include <zephyr/kernel.h>
+#include <zephyr/shell/shell.h>
+#include <lib/valve.h>
+#include <stdlib.h>
+
+static int cmd_valve_set_max_open_time(const struct shell *sh, size_t argc, char **argv)
+{
+	if (argc != 2) {
+		shell_print(sh, "Usage: valve set_max_open_time <seconds>");
+		return -EINVAL;
+	}
+
+	uint16_t seconds = (uint16_t)atoi(argv[1]);
+	valve_set_max_open_time(seconds);
+	shell_print(sh, "Max open time set to %u seconds.", seconds);
+	return 0;
+}
+
+static int cmd_valve_get_max_open_time(const struct shell *sh, size_t argc, char **argv)
+{
+	uint16_t seconds = valve_get_max_open_time();
+	shell_print(sh, "Max open time: %u seconds.", seconds);
+	return 0;
+}
+
+static int cmd_valve_set_max_close_time(const struct shell *sh, size_t argc, char **argv)
+{
+	if (argc != 2) {
+		shell_print(sh, "Usage: valve set_max_close_time <seconds>");
+		return -EINVAL;
+	}
+
+	uint16_t seconds = (uint16_t)atoi(argv[1]);
+	valve_set_max_close_time(seconds);
+	shell_print(sh, "Max close time set to %u seconds.", seconds);
+	return 0;
+}
+
+static int cmd_valve_get_max_close_time(const struct shell *sh, size_t argc, char **argv)
+{
+	uint16_t seconds = valve_get_max_close_time();
+	shell_print(sh, "Max close time: %u seconds.", seconds);
+	return 0;
+}
+
+static int cmd_valve_set_end_current_threshold_open(
+    const struct shell *sh, size_t argc, char **argv)
+{
+	if (argc != 2) {
+		shell_print(sh, "Usage: valve set_end_current_threshold_open <milliamps>");
+		return -EINVAL;
+	}
+
+	uint16_t current_ma = (uint16_t)atoi(argv[1]);
+	valve_set_end_current_threshold_open(current_ma);
+	shell_print(sh, "End current threshold (open) set to %u mA.", current_ma);
+	return 0;
+}
+
+static int cmd_valve_get_end_current_threshold_open(
+    const struct shell *sh, size_t argc, char **argv)
+{
+	uint16_t current_ma = valve_get_end_current_threshold_open();
+	shell_print(sh, "End current threshold (open): %u mA.", current_ma);
+	return 0;
+}
+
+static int cmd_valve_set_end_current_threshold_close(
+    const struct shell *sh, size_t argc, char **argv)
+{
+	if (argc != 2) {
+		shell_print(sh, "Usage: valve set_end_current_threshold_close <milliamps>");
+		return -EINVAL;
+	}
+
+	uint16_t current_ma = (uint16_t)atoi(argv[1]);
+	valve_set_end_current_threshold_close(current_ma);
+	shell_print(sh, "End current threshold (close) set to %u mA.", current_ma);
+	return 0;
+}
+
+static int cmd_valve_get_end_current_threshold_close(
+    const struct shell *sh, size_t argc, char **argv)
+{
+	uint16_t current_ma = valve_get_end_current_threshold_close();
+	shell_print(sh, "End current threshold (close): %u mA.", current_ma);
+	return 0;
+}
+
+SHELL_STATIC_SUBCMD_SET_CREATE(sub_valve_settings,
+    SHELL_CMD(set_max_open_time, NULL, "Set max open time (seconds)", cmd_valve_set_max_open_time),
+    SHELL_CMD(get_max_open_time, NULL, "Get max open time (seconds)", cmd_valve_get_max_open_time),
+    SHELL_CMD(
+        set_max_close_time, NULL, "Set max close time (seconds)", cmd_valve_set_max_close_time),
+    SHELL_CMD(
+        get_max_close_time, NULL, "Get max close time (seconds)", cmd_valve_get_max_close_time),
+    SHELL_CMD(set_end_current_threshold_open,
+        NULL,
+        "Set end current threshold for opening (mA)",
+        cmd_valve_set_end_current_threshold_open),
+    SHELL_CMD(get_end_current_threshold_open,
+        NULL,
+        "Get end current threshold for opening (mA)",
+        cmd_valve_get_end_current_threshold_open),
+    SHELL_CMD(set_end_current_threshold_close,
+        NULL,
+        "Set end current threshold for closing (mA)",
+        cmd_valve_set_end_current_threshold_close),
+    SHELL_CMD(get_end_current_threshold_close,
+        NULL,
+        "Get end current threshold for closing (mA)",
+        cmd_valve_get_end_current_threshold_close),
+    SHELL_SUBCMD_SET_END);
+
+SHELL_CMD_REGISTER(valve, &sub_valve_settings, "Valve commands", NULL);