Initial commit: bulk-link mail accounts via occ

Wrapper script around `occ mail:account:create` to bulk-link IMAP/SMTP
accounts for multiple Nextcloud users from a CSV file. Includes README
with usage, limitations (no connection test, no initial sync), and
.gitignore that blocks real credential CSVs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,8 @@
+# Echte CSV's met credentials nooit committen
+accounts.csv
+accounts.*.csv
+!accounts.example.csv
+
+# OS / editor
+.DS_Store
+*.swp