Rename project from system-stats-daemon to systant

- Updated all module names from SystemStatsDaemon to Systant
- Renamed application config from :system_stats_daemon to :systant
- Updated service files and documentation
- Release binary now at _build/prod/rel/systant/bin/systant

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

test/systant_test.exs

@@ -0,0 +1,8 @@
+defmodule SystantTest do
+  use ExUnit.Case
+  doctest Systant
+
+  test "greets the world" do
+    assert Systant.hello() == :world
+  end
+end

test/system_stats_daemon_test.exs

@@ -1,8 +0,0 @@
-defmodule SystemStatsDaemonTest do
-  use ExUnit.Case
-  doctest SystemStatsDaemon
-
-  test "greets the world" do
-    assert SystemStatsDaemon.hello() == :world
-  end
-end