macos: Ghostty.Command must copy string values (#10112)

We were previously storing the C struct which contained pointers into
ephemeral memory that could cause segfaults later on. I think this was a
tip regression, because in 1.2 despite doing this, we always referenced
static memory so it was fine. With tip, we now accept custom command
palette entries so it's dynamically allocated.

macos/Sources/Ghostty/Ghostty.Command.swift

@@ -3,28 +3,18 @@ import GhosttyKit
 extension Ghostty {
     /// `ghostty_command_s`
     struct Command: Sendable {
-        private let cValue: ghostty_command_s
-
         /// The title of the command.
-        var title: String {
-            String(cString: cValue.title)
-        }
+        let title: String
 
         /// Human-friendly description of what this command will do.
-        var description: String {
-            String(cString: cValue.description)
-        }
+        let description: String
 
         /// The full action that must be performed to invoke this command.
-        var action: String {
-            String(cString: cValue.action)
-        }
+        let action: String
 
         /// Only the key portion of the action so you can compare action types, e.g. `goto_split`
         /// instead of `goto_split:left`.
-        var actionKey: String {
-            String(cString: cValue.action_key)
-        }
+        let actionKey: String
 
         /// True if this can be performed on this target.
         var isSupported: Bool {
@@ -40,7 +30,10 @@ extension Ghostty {
         ]
 
         init(cValue: ghostty_command_s) {
-            self.cValue = cValue
+            self.title = String(cString: cValue.title)
+            self.description = String(cString: cValue.description)
+            self.action = String(cString: cValue.action)
+            self.actionKey = String(cString: cValue.action_key)
         }
     }
 }