chore: repo scaffolding — gitignore and .claude settings

Ignore the Walkers symlink (live game saves), snapshots/, the large
regenerable il2cpp/ dumps, and Python cruft. Carry over the project
permission allowlist in .claude/settings.local.json.

.claude/settings.local.json

@@ -0,0 +1,18 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(python3 *)",
+      "Read(//mnt/c/Users/DownloadPizza/Downloads/yoten/**)",
+      "Bash(sed -n '12482,12700p' il2cpp/dump.cs)",
+      "Bash(grep *)",
+      "WebFetch(domain:pymongo.readthedocs.io)",
+      "Bash(~/sand_tools/venv/bin/pip list *)",
+      "Bash(~/sand_tools/venv/bin/python -c \"import bson; print\\('path:', bson.__file__\\); import os; print\\('listing:', os.listdir\\(os.path.dirname\\(bson.__file__\\) or '.'\\)\\)\")",
+      "Bash(~/sand_tools/venv/bin/pip install *)",
+      "Bash(awk 'NR==12365 || NR==42609 || NR==43154 || NR==43182' /mnt/c/Users/DownloadPizza/AppData/LocalLow/Hologryph/SAND/Data/Walkers/dump.cs)",
+      "Bash(~/sand_tools/venv/bin/python *)",
+      "Read(//home/downloadpizza/sand_tools/**)",
+      "Bash(venv/bin/python -)"
+    ]
+  }
+}