chore: add precon-decks, card images, and Unity generated files to .gitignore

.gitignore

@@ -38,3 +38,32 @@ Thumbs.db
 
 # Logs
 *.log
+
+# Precon decks — runtime data, downloaded locally by Forge/scripts
+# Do not commit .dck files; they are large and machine-generated
+precon-decks/*.dck
+precon-decks/precon-index.json
+
+# Phase 0: Local Scryfall card image cache (~1.5-2GB)
+# Downloaded by scripts/download_card_images.py — never commit
+static/card-images/
+
+# Phase 0: SQLite image index (generated by scripts/build_image_index.py)
+data/card_image_index.db
+
+# Phase 6: AI decision logs and training sets (large runtime data)
+data/decision_logs/
+data/game_results.jsonl
+data/training_sets/
+
+# Unity generated / local config files
+unity-client/Packages/packages-lock.json
+unity-client/ProjectSettings/EditorBuildSettings.asset
+unity-client/ProjectSettings/EditorSettings.asset
+unity-client/ProjectSettings/ShaderGraphSettings.asset
+unity-client/Assets/TcgEngine/Render/URP-HIGH.asset
+unity-client/Assets/TcgEngine/Render/URP-LOW.asset
+unity-client/Assets/TcgEngine/Render/URP-MEDIUM.asset
+unity-commander-ui/Packages/packages-lock.json
+unity-commander-ui/ProjectSettings/EditorBuildSettings.asset
+unity-commander-ui/ProjectSettings/EditorSettings.asset