chore: Add initial Unity package manifest and lock files with project dependencies.

Packages/manifest.json

@@ -1,10 +1,9 @@
 {
   "dependencies": {
+    "com.heavycaffiner.ide.antigravity": "https://github.com/heavycaffeiner/com.heavycaffeiner.ide.antigravity.git",
     "com.kyrylokuzyk.primetween": "file:../Assets/Plugins/PrimeTween/internal/com.kyrylokuzyk.primetween.tgz",
     "com.unity.2d.sprite": "1.0.0",
-    "com.unity.ai.navigation": "2.0.9",
     "com.unity.collab-proxy": "2.10.2",
-    "com.unity.ide.rider": "3.0.38",
     "com.unity.ide.visualstudio": "2.0.25",
     "com.unity.inputsystem": "1.14.2",
     "com.unity.multiplayer.center": "1.0.0",

Packages/packages-lock.json

@@ -1,5 +1,14 @@
 {
   "dependencies": {
+    "com.heavycaffiner.ide.antigravity": {
+      "version": "https://github.com/heavycaffeiner/com.heavycaffeiner.ide.antigravity.git",
+      "depth": 0,
+      "source": "git",
+      "dependencies": {
+        "com.unity.test-framework": "1.1.31"
+      },
+      "hash": "bbdfe7c97d7c662964e425bd56cc3728846e09ff"
+    },
     "com.kyrylokuzyk.primetween": {
       "version": "file:../Assets/Plugins/PrimeTween/internal/com.kyrylokuzyk.primetween.tgz",
       "depth": 0,
@@ -12,15 +21,6 @@
       "source": "builtin",
       "dependencies": {}
     },
-    "com.unity.ai.navigation": {
-      "version": "2.0.9",
-      "depth": 0,
-      "source": "registry",
-      "dependencies": {
-        "com.unity.modules.ai": "1.0.0"
-      },
-      "url": "https://packages.unity.com"
-    },
     "com.unity.burst": {
       "version": "1.8.25",
       "depth": 2,
@@ -57,15 +57,6 @@
       "source": "builtin",
       "dependencies": {}
     },
-    "com.unity.ide.rider": {
-      "version": "3.0.38",
-      "depth": 0,
-      "source": "registry",
-      "dependencies": {
-        "com.unity.ext.nunit": "1.0.6"
-      },
-      "url": "https://packages.unity.com"
-    },
     "com.unity.ide.visualstudio": {
       "version": "2.0.25",
       "depth": 0,