chore: gitignore Rust target/ build output (#1084)

Cargo writes build artifacts (582MB locally) to the workspace target/
directory at repo root. This was not gitignored, leaving status output
noisy and risking accidental commits of build output.

Author: carlos-alm

.gitignore

@@ -12,3 +12,4 @@ generated/DEPENDENCIES.md
 generated/DEPENDENCIES.json
 artifacts/
 pkg/
+target/