docs: Add RustChain dependency management guide (#1678)

.gitignore

@@ -1,5 +1,50 @@
-__pycache__/
-*.pyc
+# Generated by Cargo
+/target/
+**/target/
 
-# Generated scan artifacts
-reports/
+# Cargo.lock for libraries (keep for binaries)
+# Cargo.lock
+
+# IDE and editors
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+.DS_Store
+
+# RustAnalyzer
+/rust-analyzer/
+
+# Build output
+*.rs.bk
+*.pdb
+
+# Keys and sensitive data (NEVER commit these!)
+*.key
+*.pem
+*.bin
+!Cargo.lock
+
+# Config files with secrets
+config.local.toml
+.env
+.env.local
+
+# Test artifacts
+*.out
+*.log
+test_*.bin
+
+# Benchmarks
+/criterion/
+
+# Coverage
+*.gcno
+*.gcda
+coverage/
+*.lcov
+
+# Profiling
+*.profraw
+*.profdata