chore: remove Cargo.lock and bump to v0.3.2

Library crates should not commit Cargo.lock files. Only application
crates need Cargo.lock for reproducible builds.

This ensures library users control their own dependency resolution
rather than being locked to specific versions from the library's
lock file.

Changes:
- Add Cargo.lock to .gitignore (was missing from ignore patterns)
- Delete committed Cargo.lock file from repository (1475 lines)
- Bump version to 0.3.2 in both crates
- Update CHANGELOG.md with 0.3.2 release notes
- Update scripts/release_check.sh version to 0.3.2

scripts/release_check.sh

@@ -7,7 +7,7 @@ set -e
 # =============================================================================
 # CONFIGURATION
 # =============================================================================
-VERSION="0.3.1"
+VERSION="0.3.2"
 
 echo "=================="
 echo "dagx Release Check"