Chem guidebook (#17123)

* im good at atomizing. welcome to half-finished chem guides.

* wagh

* e

* save work

* aa

* woweee UI

* finishing the last of it

* don't actually update the engine :(

---------

Co-authored-by: moonheart08 <moonheart08@users.noreply.github.com>

Content.Client/Chemistry/EntitySystems/ChemistryGuideDataSystem.cs

@@ -0,0 +1,29 @@
+using Content.Shared.Chemistry;
+
+namespace Content.Client.Chemistry.EntitySystems;
+
+/// <inheritdoc/>
+public sealed class ChemistryGuideDataSystem : SharedChemistryGuideDataSystem
+{
+    /// <inheritdoc/>
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeNetworkEvent<ReagentGuideRegistryChangedEvent>(OnReceiveRegistryUpdate);
+    }
+
+    private void OnReceiveRegistryUpdate(ReagentGuideRegistryChangedEvent message)
+    {
+        var data = message.Changeset;
+        foreach (var remove in data.Removed)
+        {
+            Registry.Remove(remove);
+        }
+
+        foreach (var (key, val) in data.GuideEntries)
+        {
+            Registry[key] = val;
+        }
+    }
+}