chore: add Input System package and ignore TMP font assets

- Add com.unity.inputsystem package dependency
- Ignore TextMesh Pro auto-generated font assets in gitignore

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

unity-client/Packages/packages-lock.json

@@ -238,6 +238,15 @@
         "com.unity.2d.tooling": "1.0.0"
       }
     },
+    "com.unity.inputsystem": {
+      "version": "1.17.0",
+      "depth": 0,
+      "source": "registry",
+      "dependencies": {
+        "com.unity.modules.uielements": "1.0.0"
+      },
+      "url": "https://packages.unity.com"
+    },
     "com.unity.mathematics": {
       "version": "1.3.3",
       "depth": 1,