ui(pool): pick an account's users from its own Edit

Each account row in the Account pool card has a pencil: tick the users
whose sessions run on it (one moves off any other account, unticking sends
one back to the balancer). PUT /api/accounts/:name/users saves the set in one
transaction, audits each change and switches a Claude login into each added
user's home at once. The card-level switch button and pinned list are gone.

client/src/i18n/locales/en/users.json

@@ -199,28 +199,18 @@
     },
     "refreshFailed": "refresh failed",
     "pinned": "Used by: {{users}}",
-    "pinUser": "Switch a user's account",
-    "pinTitle": "Switch a user's account",
-    "pinHint": "That user's sessions run on the chosen account instead of the least-used one — even when it is full. A Claude login is written into their home at once: sessions already running move to it at their next login check, with no restart. A setup-token or Codex account applies to new sessions.",
-    "pinButton": "Switch",
-    "user": "User",
-    "chooseUser": "Choose a user…",
     "loadingUsers": "Loading…",
-    "pinAccount": "Account",
-    "noPin": "Automatic — the least-used account",
-    "pinsTitle": "Switched users",
-    "unpin": "Back to automatic for {{name}}",
     "pinDone": {
-      "pinned": "{{user}} now runs on {{account}}",
-      "unpinned": "{{user}} is back on the least-used account",
-      "switched": "{{user}} switched to {{account}} — running sessions follow at their next login check",
       "own-login": "{{user}} signed in with their own login, which was left alone",
       "expired": "{{account}} has expired — {{user}}'s new sessions fall back to the least-used account"
     },
-    "toolName": {
-      "claude": "Claude",
-      "codex": "Codex"
-    }
+    "edit": "Edit {{name}}",
+    "editHint": "Tick the users whose sessions run on this account instead of the least-used one — even when it is full. A user on another account moves here. A Claude login is written into their home at once: sessions already running move to it at their next login check, with no restart. A setup-token or Codex account applies to new sessions. Untick to send a user back to the least-used account.",
+    "save": "Save",
+    "users": "Users on this account",
+    "noUsers": "No users yet.",
+    "onAccount": "now on {{account}}",
+    "editDone": "{{name}} saved"
   },
   "delete": {
     "button": "Delete user",