feat(notify): add notif to internal users when granted

- add coalesced protection to avoid mail bombing if an invited goes many grant in a short period
    - add resentd method in share menu item (work for both internal and external users)
    - user can disable email notification via his properties
    - add env variable from admin to disable notifications

example.env

@@ -416,6 +416,26 @@ OXICLOUD_WOPI_ENABLED=false
 # IdP is the security boundary and may enforce MFA we shouldn't bypass.
 #OXICLOUD_MAGIC_LINK_OPEN_TO_PASSWORD_USERS=false
 
+# Operator-level kill switch for share-notification emails to internal
+# users (the "Alice shared 'Project Alpha' with you" mail that fires when
+# `magic_link_eligibility` rejects the recipient — typically password
+# users and OIDC users with a known email). When `true` (default), the
+# new RecipientNotificationService dispatches plain-notification mail
+# on every share. When `false`, internal users discover new shares only
+# at next login.
+#
+# This is a coarser knob than the per-user
+# `auth.users.notify_on_share` column (set via the profile "Email me
+# when someone shares with me" checkbox): when this env is `false`,
+# the per-user opt-in does not matter.
+#
+# External-user magic-link FIRST-invitations are NOT affected by this
+# flag — those always send, because the link is the only way the
+# recipient can claim the share for the first time. Subsequent shares
+# to an existing external follow the same plain-notification path and
+# are subject to both this knob and the per-user opt-out.
+#OXICLOUD_NOTIFY_INTERNAL_USERS_ON_SHARE=true
+
 # -----------------------------------------------------------------------------
 # INTERNATIONALIZATION (server-rendered surfaces)
 # -----------------------------------------------------------------------------