feat(ui): overridable favicon/logo with branded default

Replace the ⚓ emoji with a real logo image used as the in-app brand
mark and the favicon. Default bundled public/logo.svg is the
HangmanLab mark recolored to the Foundry-Deck ember (#ff6a1a).
Override at deploy time via HARBORFORGE_LOGO_URL (injected into
runtime-config.js; getLogoUrl() + favicon swap), no rebuild needed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/Sidebar.tsx

@@ -2,6 +2,7 @@ import { useState, useEffect } from 'react'
 import { Link, useLocation, useNavigate } from 'react-router-dom'
 import api from '@/services/api'
 import { useAuthConfig, oidcLinkHref } from '@/hooks/useAuthConfig'
+import { getLogoUrl } from '@/runtime'
 import type { User } from '@/types'
 
 interface Props {
@@ -50,7 +51,7 @@ export default function Sidebar({ user, onLogout }: Props) {
   return (
     <nav className="sidebar">
       <div className="sidebar-header">
-        <h1>⚓ HarborForge</h1>
+        <h1><img src={getLogoUrl()} className="brand-logo" alt="" /> HarborForge</h1>
       </div>
       <ul className="nav-links">
         {links.map((l) => (