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/docs_api/join.py

@@ -21,5 +21,31 @@ GROUP = {
             sample={"ok": True, "redirect": "/join?ok=1", "data": {"uid": "0190..."}},
             probe_body={"name": "Probe", "contact": "probe@example.com"},
         ),
+        endpoint(
+            "GET",
+            "/invite/{token}",
+            "Invite claim form",
+            "Shows the claim form for a live invite; unknown, used and expired links answer 404 with the same message.",
+            fields=[field("token", required=True, location="path", example="unknown-token")],
+            sample={"valid": True, "username": "ada", "email": "ada@example.com", "email_locked": True},
+            probe_path="/invite/unknown-token",
+        ),
+        endpoint(
+            "POST",
+            "/invite/{token}",
+            "Claim invite",
+            "Creates the Member account, logs in and marks the join request accepted. Single use.",
+            fields=[
+                field("token", required=True, location="path", example="unknown-token"),
+                field("username", required=True, example="ada"),
+                field("email", required=True, example="ada@example.com"),
+                field("password", required=True, example="correct horse battery staple"),
+                field("password_confirm", required=True, example="correct horse battery staple"),
+                field("terms", required=True, type="boolean", example=True),
+            ],
+            sample={"ok": True, "redirect": "/", "data": {"username": "ada"}},
+            probe_path="/invite/unknown-token",
+            probe_body={"username": "Probe", "email": "probe@example.com", "password": "probe-pass-1", "password_confirm": "probe-pass-1", "terms": True},
+        ),
     ],
 }