chore: sync changes with ghostty_string_s

include/ghostty.h

@@ -353,7 +353,7 @@ typedef struct {
 typedef struct {
   const char* ptr;
   uintptr_t len;
-  uintptr_t cap;
+  bool sentinel;
 } ghostty_string_s;
 
 typedef struct {

src/config/CApi.zig

@@ -130,7 +130,6 @@ export fn ghostty_config_open_path() c.String {
         return .empty;
     };
 
-    // Capacity is len + 1 due to sentinel
     return .fromSlice(path);
 }