Remove overly broad *.json from .gitignore

The blanket *.json ignore is not canonical for Rust projects.
JSON files that need ignoring are already covered by:
- .g3/ for session logs
- logs/ for error logs
- .build for Swift build artifacts

.gitignore

@@ -25,10 +25,6 @@ target
 
 # Session logs directory
 logs/
-*.json
-# Exception: analysis artifacts
-!analysis/deps/graph.json
-
 .g3/
 
 # g3 artifacts