chore(gitignore): ignore per-package runtime data dirs (**/data/)

The root /data/ rule is anchored to the repo root and missed
packages/<pkg>/data/<uin>/*.db that IdentityService writes to cwd during
tests. Add a recursive **/data/ so those test artifacts stay untracked.

.gitignore

@@ -11,6 +11,9 @@ dist/
 
 /config/
 /data/
+# per-package runtime data dirs (e.g. packages/core/data/<uin>/*.db written by
+# IdentityService during tests) — not just the root /data/
+**/data/
 logs/
 
 # macOS metadata