Refactor Json to JsonMapper, update Gradle to 9.5.1, and set Java 26 toolchain.

src/main/java/dev/coph/nextusweb/server/router/Request.java

@@ -1,6 +1,6 @@
 package dev.coph.nextusweb.server.router;
 
-import dev.coph.nextusweb.server.json.Json;
+import dev.coph.nextusweb.server.json.JsonMapper;
 import dev.coph.nextusweb.server.router.exception.BadRequestException;
 import io.netty.handler.codec.http.*;
 import io.netty.util.CharsetUtil;
@@ -54,9 +54,9 @@ public final class Request {
                 byte[] bytes = new byte[raw.content().readableBytes()];
                 raw.content().getBytes(raw.content().readerIndex(), bytes);
                 if (bytes.length == 0) {
-                    jsonCache = Json.MAPPER.nullNode();
+                    jsonCache = JsonMapper.MAPPER.nullNode();
                 } else {
-                    jsonCache = Json.MAPPER.readTree(bytes);
+                    jsonCache = JsonMapper.MAPPER.readTree(bytes);
                 }
             } catch (JacksonException e) {
                 throw new BadRequestException("Invalid JSON: " + e.getOriginalMessage());
@@ -69,7 +69,7 @@ public final class Request {
         try {
             byte[] bytes = new byte[raw.content().readableBytes()];
             raw.content().getBytes(raw.content().readerIndex(), bytes);
-            return Json.MAPPER.readValue(bytes, type);
+            return JsonMapper.MAPPER.readValue(bytes, type);
         } catch (JacksonException e) {
             throw new BadRequestException(
                     "Could not deserialize body as " + type.getSimpleName() + ": " + e.getOriginalMessage());