chore: add agent-skills config, glossary and example mod

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.examples/ug_tf3_example_config_change/mod.json

@@ -0,0 +1,10 @@
+{
+    "modId": "ug_tf3_config_change",
+    "revision": 1,
+    "severityAdd": "None",
+    "severityRemove": "Warning",
+    "cosmetic": false,
+    "preRunScript": {
+        "fileName": "ug_tf3_config_change::mod.script@preRunFn"
+    }
+}