fix: resolve Docker build issues

- Update .gitignore to allow moveIndex.json (needed at build time)
- Exclude only eco*.json files (too large for git)
- Add uuid package dependency for sessionManager

Fixes:
- Next.js build error: Module not found moveIndex.json
- Build error: Module not found uuid

.gitignore

@@ -58,8 +58,14 @@ __pycache__/
 *.pgn
 *.pgn.zst
 
-# Generated opening and Wikipedia data (fetched at Docker startup)
-/public/openings/*.json
+# Opening database files (too large for git, users must provide)
+/public/openings/eco*.json
+
+# Generated move index (should be committed)
+# Note: moveIndex.json is generated from eco files but needs to be in git
+# because Next.js imports it at build time
+
+# Wikipedia data (fetched at Docker startup)
 /public/wikipedia/*.json
 /public/wikipedia/.initialized