mp regeneration

using nethack calcs as a placeholder for now

src/components.rs

@@ -190,6 +190,17 @@ pub struct Skills {
     pub skills: HashMap<Skill, i32>,
 }
 
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct KnownSpell {
+    pub display_name: String,
+    pub mana_cost: i32,
+}
+
+#[derive(Component, Debug, Serialize, Deserialize, Clone)]
+pub struct KnownSpells {
+    pub spells: Vec<KnownSpell>,
+}
+
 #[derive(Component, Debug, Serialize, Deserialize, Clone)]
 pub struct Attributes {
     pub strength: Attribute,