Fix #23743: Park with > 32k guests goal not in scenario list

Creating the scenario cache file tried to read the guest count as signed 16 bit value which doesn't work for values > 32k.  In addition ObjectiveArg3 (variable to store guest count) is an signed value, unable to store 50k guests.

distribution/changelog.txt

@@ -2,6 +2,7 @@
 ------------------------------------------------------------------------
 - Fix: [#4225] Ride Construction window offers non-existent banked sloped to level curve (original bug).
 - Fix: [#10379] Banners outside the park can be renamed and modified (original bug).
+- Fix: [#23743] Parks with guest goals over 32767 do not appear in the scenario list.
 - Fix: [#23844] Sound effects keep playing when loading another save.
 - Fix: [#23897] Reverse Freefall Coaster slope up to vertical track piece does not draw a vertical tunnel.
 

src/openrct2/park/ParkFile.cpp

@@ -224,9 +224,10 @@ namespace OpenRCT2
                 ReadWriteStringTable(cs, scenarioDetails, "en-GB");
                 entry.Details = scenarioDetails;
 
+                // wrong order is intentional here due to ReadWriteScenarioChunk writing guests first
                 entry.ObjectiveType = cs.Read<uint8_t>();
                 entry.ObjectiveArg1 = cs.Read<uint8_t>();
-                entry.ObjectiveArg3 = cs.Read<int16_t>();
+                entry.ObjectiveArg3 = cs.Read<uint16_t>();
                 entry.ObjectiveArg2 = cs.Read<int32_t>();
 
                 entry.SourceGame = ScenarioSource::Other;

src/openrct2/rct2/RCT2.h

@@ -393,7 +393,7 @@ namespace OpenRCT2::RCT2
         int8_t ObjectiveType;
         int8_t ObjectiveArg1;
         int32_t objectiveArg2;
-        int16_t objectiveArg3;
+        uint16_t objectiveArg3;
         char Name[64];
         char Details[256];
         int32_t Flags;
@@ -758,11 +758,11 @@ namespace OpenRCT2::RCT2
     struct S6Info
     {
         ::EditorStep EditorStep;
-        uint8_t Category;      // 0x01
-        uint8_t ObjectiveType; // 0x02
-        uint8_t ObjectiveArg1; // 0x03
-        int32_t ObjectiveArg2; // 0x04
-        int16_t ObjectiveArg3; // 0x08
+        uint8_t Category;       // 0x01
+        uint8_t ObjectiveType;  // 0x02
+        uint8_t ObjectiveArg1;  // 0x03
+        int32_t ObjectiveArg2;  // 0x04
+        uint16_t ObjectiveArg3; // 0x08
         uint8_t Pad00A[0x3E];
         char Name[64];        // 0x48
         char Details[256];    // 0x88

src/openrct2/scenario/ScenarioRepository.h

@@ -52,9 +52,9 @@ struct ScenarioIndexEntry
 
     // Objective
     uint8_t ObjectiveType;
-    uint8_t ObjectiveArg1;
-    int64_t ObjectiveArg2;
-    int16_t ObjectiveArg3;
+    uint8_t ObjectiveArg1;  // years
+    int64_t ObjectiveArg2;  // money or excitement
+    uint16_t ObjectiveArg3; // guests or rideID or coasterLength
     ScenarioHighscoreEntry* Highscore = nullptr;
 
     u8string InternalName; // Untranslated name