Member invites, gallery resync, content and operator docs

- Invite flow: admin issue/revoke on join requests, public single-use
  claim links (hash-only tokens, 7-day expiry, no state reveal), claim
  creates the Member account and marks the request accepted
- Gallery: admin status page plus resync endpoint; sync refreshes
  thumbnails whose content changed; tools/gallery contract and checker
- Docs: public content page, admin-only operator runbook, api.md
  invite/gallery sections, all routes in the live API docs, docs
  reachability gate test
- Screenshots cover the new pages; version 1.0.18

molodetz/database/__init__.py

@@ -20,6 +20,15 @@ from molodetz.database.core import (
     table_exists,
 )
 from molodetz.database.init_db import init_db
+from molodetz.database.invites import (
+    claim_invite,
+    create_invite,
+    get_invite_by_token,
+    invite_is_live,
+    open_invite_for_join,
+    revoke_open_invites,
+    suggest_username,
+)
 from molodetz.database.joins import (
     count_open_join_requests,
     get_join_request,
@@ -97,6 +106,8 @@ __all__ = [
     "count_open_join_requests",
     "count_published",
     "count_users",
+    "claim_invite",
+    "create_invite",
     "create_session",
     "create_user",
     "daily_totals",
@@ -110,6 +121,7 @@ __all__ = [
     "generate_uid",
     "get_backup",
     "get_int_setting",
+    "get_invite_by_token",
     "get_join_request",
     "get_post",
     "get_post_by_slug",
@@ -128,6 +140,7 @@ __all__ = [
     "insert_notification",
     "insert_post",
     "invalidate_admins_cache",
+    "invite_is_live",
     "list_audit",
     "list_backups",
     "list_deleted",
@@ -138,6 +151,7 @@ __all__ = [
     "mark_all_read",
     "media_by_kind",
     "now_iso",
+    "open_invite_for_join",
     "paginate",
     "parse_iso",
     "pending_backups",
@@ -152,11 +166,13 @@ __all__ = [
     "resolve_by_slug",
     "restore",
     "restore_event",
+    "revoke_open_invites",
     "set_role",
     "set_setting",
     "shard_path",
     "soft_delete",
     "soft_delete_in",
+    "suggest_username",
     "sync_local_cache",
     "table_exists",
     "top_paths",