B4 frontend: probe task management modal on the nodes page

- ProbeTasksModal: self-loading/self-saving surface (B3 probe-meta
  pattern), tasks grouped by region label (ungrouped last), editor
  with name/region/target/interval/auto-join + agent-node multi
  select snapshotting baseNodeIds for the base-diff save; delete
  with confirm. Toolbar entry on NodeList (RadarChart icon), wired
  in NodesPage; NodeList call sites in two component tests updated
  for the new required prop.
- i18n pages.nodes.probeTasks.* (25 keys) in all 13 locales: zh-CN
  translated, en-US English, others English placeholder per repo
  convention; insertion verified pure-additive (351 insertions,
  0 deletions) and the i18n dead-key failures are byte-identical
  to the B3 baseline.
- tsc clean; oxlint 0/0 (baseline parity); oxfmt clean on touched
  files (3 pre-existing drift files untouched).

internal/web/translation/ru-RU.json

@@ -959,6 +959,33 @@
         "save": "Save status page info",
         "saved": "Status page info saved",
         "saveFailed": "Saving status page info failed"
+      },
+      "probeTasks": {
+        "title": "Probe tasks",
+        "intro": "TCP latency probes run by agent nodes. Changes apply on each agent's next config poll (about 30 s); nothing restarts.",
+        "loading": "Loading…",
+        "empty": "No probe tasks yet. Add one to start measuring latency.",
+        "add": "Add probe",
+        "name": "Name",
+        "target": "Target",
+        "targetPlaceholder": "host:port, e.g. 1.1.1.1:443",
+        "interval": "Interval (s)",
+        "region": "Region",
+        "ungrouped": "Ungrouped",
+        "autoJoin": "Auto-join",
+        "autoJoinOn": "Auto",
+        "nodes": "Nodes",
+        "nodesPlaceholder": "Assign nodes",
+        "actions": "Actions",
+        "edit": "Edit",
+        "delete": "Delete",
+        "deleteConfirm": "Delete this probe and its history?",
+        "save": "Save",
+        "cancel": "Cancel",
+        "saved": "Probe task saved",
+        "deleted": "Probe task deleted",
+        "loadFailed": "Failed to load probe tasks",
+        "saveFailed": "Operation failed"
       }
     },
     "settings": {