feat(shard): Protocol 2.0 boards UI — guilds, governors, houses, players-online

Phase 2: the public UI for the four new boards, following the ChampSpawns live
pattern (snapshot via useAsync + merge SSE deltas with useShardFeed).

- Players Online widget (components/PlayersOnline.jsx): total + region breakdown
  rolled up into display buckets (data/regionBuckets.js — the one place to retune
  the grouping); live via presence.online. Placed on the Shard page, replacing the
  static players-online stat tile.
- Guilds (/site/guilds): searchable board of rosters/alliances/leaders with a
  "recently joined" strip from guild.join.
- Governors (/site/governors): one card per city with a placeholder crest
  (data/cityCrests.js — swap for real art without touching components), election
  phase badge + autoPickAt countdown, and an on-demand "past governors" term
  history (the look-back reads the ledger captured in Phase 1). Clean empty state
  when City Loyalty isn't enabled.
- Houses (/site/houses): searchable registry with decay badges; price labelled
  "placement value", not a for-sale flag.
- API client methods + nav links (Guilds / Governors / Houses).

Client build clean (240 modules).

Refs .plans/protocol2-integration.md (Phase 2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/api/client.js

@@ -95,6 +95,13 @@ export const api = {
     online: () => req('/public/shard/online'),
     idoc: () => req('/public/shard/idoc'),
     champs: () => req('/public/shard/champs'),
+    // Protocol 2.0 boards.
+    guilds: () => req('/public/shard/guilds'),
+    governors: () => req('/public/shard/governors'),
+    governorHistory: (city, limit) =>
+      req(`/public/shard/governors/${encodeURIComponent(city)}/history${limit ? `?limit=${limit}` : ''}`),
+    presence: () => req('/public/shard/presence'),
+    houses: () => req('/public/shard/houses'),
   },
   // Full paths (incl. /api/v1) for the browser EventSource — the req() wrapper is
   // fetch-only, so SSE subscribers build the URL from here. The admin stream