fix: resolve dialyzer warnings in device_live/index.ex

Convert compile-time module attributes to runtime functions to avoid
dialyzer warnings about compile-time constant comparisons:

- tick_interval_ms: function instead of @tick_interval_ms
- debounce_ms: function instead of @debounce_ms

This fixes warnings where dialyzer knew the comparisons could never
be false/true based on compile-time values.

lib/towerops_web/live/device_live/index.ex

@@ -282,15 +282,20 @@ defmodule ToweropsWeb.DeviceLive.Index do
     {:noreply, reload_device_stream(socket)}
   end
 
-  @tick_interval_ms if Mix.env() == :test, do: :infinity, else: to_timeout(second: 15)
+  defp tick_interval_ms do
+    if Mix.env() == :test, do: :infinity, else: to_timeout(second: 15)
+  end
 
   defp schedule_tick do
-    if @tick_interval_ms != :infinity do
-      Process.send_after(self(), :tick, @tick_interval_ms)
+    case tick_interval_ms() do
+      :infinity -> :ok
+      interval -> Process.send_after(self(), :tick, interval)
     end
   end
 
-  @debounce_ms if Mix.env() == :test, do: 0, else: 100
+  defp debounce_ms do
+    if Mix.env() == :test, do: 0, else: 100
+  end
 
   defp schedule_debounced_reload(socket, event) do
     # Cancel any pending debounced reload
@@ -302,12 +307,14 @@ defmodule ToweropsWeb.DeviceLive.Index do
     if event == :device_status_changed && socket.assigns.active_tab == "discovered" do
       assign(socket, :pending_reload_ref, nil)
     else
-      if @debounce_ms == 0 do
-        # In test: reload immediately so render(view) sees the update
-        reload_device_stream(socket)
-      else
-        ref = Process.send_after(self(), :debounced_device_reload, @debounce_ms)
-        assign(socket, :pending_reload_ref, ref)
+      case debounce_ms() do
+        0 ->
+          # In test: reload immediately so render(view) sees the update
+          reload_device_stream(socket)
+
+        ms ->
+          ref = Process.send_after(self(), :debounced_device_reload, ms)
+          assign(socket, :pending_reload_ref, ref)
       end
     end
   end