feat(dashboard): open Player Dashboard in a new tab

The 👥 Dashboard button used to open the player table as a draggable
in-app window, which competed for screen space with the map. It now
opens in a separate browser tab as a fullscreen page so users can put
the dashboard on a second monitor.

How:
- App.tsx branches on ?view=dashboard → renders PlayerDashboardFullPage
  (new file in components/) instead of the default MapLayout.
- SidebarWindowButtons.tsx: 👥 Dashboard onClick now does
  window.open('/?view=dashboard', '_blank', 'noopener'). Label shows
  '↗' so users know it's an external open.
- PlayerDashboardWindow.tsx refactored: extracted the sortable table
  body into a reusable PlayerDashboardContent component. The old window
  shell stays registered in WindowRenderer for backward compat — just
  no longer reachable from the default sidebar.
- map-layout.css: new .ml-dashboard-page rules for fullscreen layout.

Each tab gets its own useLiveData + WebSocket connection (server
already handles multiple browser clients). The new tab inherits the
session cookie from the original tab — no re-login.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

static/assets/CombatPickerWindow-2NQUGplv.js

@@ -1 +0,0 @@
-import{u as c,j as r,D as d}from"./index-3SHiQu4l.js";import"./react-yfL0ty4i.js";const p=({id:n,zIndex:i,characters:a})=>{const{openWindow:s}=c(),e=Array.from(a.keys()).sort();return r.jsx(d,{id:n,title:"Combat Stats — Select Character",zIndex:i,width:300,height:400,children:r.jsx("div",{style:{flex:1,overflowY:"auto",padding:6},children:e.length===0?r.jsx("div",{style:{padding:12,color:"#666",textAlign:"center",fontSize:"0.8rem"},children:"No characters online"}):e.map(o=>r.jsx("div",{style:{padding:"5px 8px",cursor:"pointer",borderBottom:"1px solid #222",color:"#ccc",fontSize:"0.82rem"},onMouseEnter:t=>t.currentTarget.style.background="#2a2a2a",onMouseLeave:t=>t.currentTarget.style.background="",onClick:()=>s(`combat-${o}`,`Combat: ${o}`,o),children:o},o))})})};export{p as CombatPickerWindow};