feat(rust): Dynamic PVP's zones on the feed and the map (PLAN_REDESIGNS §14.3.3)

Stage 4 of the §14.3 integration plan, on protocol 14 (docs
rust-link/PROTOCOL.md §20.7).

- pvp.zone.created is a public kind, pvp.zone.deleted a staff kind. Each row
  is read per viewer by the new dynamicPvp.js: grid for everyone, the event's
  name only for Dynamic PVP's own vanilla events, position and zone id for
  staff only.
- The feed's world filter carries the opening: "A PvP zone opened around the
  downed patrol helicopter · G7 · for 10 min". It names nobody.
- The map gains a fifth layer, `pvp` (PvP zones), public by default with its
  own audience in Admin → Rust visibility, drawn as a red ring with its
  event's name.
- Server settings' plugin line names Dynamic PVP; the swagger schemas and
  route descriptions carry the layer and the integration (fragment
  regenerated); ci/bundle.json ships dynamicPvp.js; README lists it.

Tests: server 611/611 (dynamicPvp.test.js new, catalogue and map extended)
and every check; client 89/89 (feed and map tooltip), build and externals.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

client/src/routes/admin/Visibility.jsx

@@ -384,6 +384,7 @@ const MAP_LAYERS = [
   { id: 'events', label: 'Site events', hint: 'The zones, crates and NPCs this site’s events placed, while they run.' },
   { id: 'players', label: 'Players', hint: 'Where everybody is, with names, and the sleepers.' },
   { id: 'bases', label: 'Bases', hint: 'Tool cupboards and vending machines, as positions only.' },
+  { id: 'pvp', label: 'PvP zones', hint: 'Dynamic PVP’s own PvP zones around a downed helicopter, a Bradley, cargo and the rest. Needs Dynamic PVP on the server.' },
 ]
 
 const RANK = { public: 0, signed_in: 1, staff: 2 }