Add web admin panel for accounts/characters (login, GM rights, live stats)

New "webadmin" service (Flask + PyMySQL, port 8081) backing a small
server-rendered admin UI:
- Login gated on an existing game account: only accounts with
  accesslevel >= ADMIN_MIN_ACCESSLEVEL (default 900) get in. Password
  is MD5-hashed before comparison since the game client hashes it
  client-side before it ever hits the wire -- accounts.password is
  always an MD5 hex digest, confirmed against existing DB rows.
- Accounts: list/search, create, edit accesslevel/active/password.
- Characters: list/search, create (mirrors the real char-creation
  INSERT in Src/Char Server/charpackets.cpp -- only account_name,
  char_name, face, hairStyle, sex are set, everything else relies on
  the table's own defaults), edit core stats (level, zuly, attributes,
  hp/mp, stat/skill points) and isgm/isdev flags directly.

All queries are parameterized (no string-formatted SQL). No CSRF
protection or rate limiting yet -- acceptable for a small
already-behind-a-high-accesslevel-gate private server, worth
revisiting before ever exposing this port publicly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

webadmin/templates/characters.html

@@ -0,0 +1,25 @@
+{% extends "base.html" %}
+{% block title %}Charaktere - ROSS Admin{% endblock %}
+{% block content %}
+<div class="searchbar">
+  <form method="get" style="display:flex;gap:10px;flex:1;">
+    <input type="text" name="q" placeholder="Charakter- oder Accountname suchen..." value="{{ q }}">
+    <button type="submit">Suchen</button>
+  </form>
+  <a class="btn" href="{{ url_for('new_character') }}">+ Neuer Charakter</a>
+</div>
+<table>
+  <tr><th>ID</th><th>Name</th><th>Account</th><th>Level</th><th>GM</th><th>Dev</th><th></th></tr>
+  {% for c in chars %}
+  <tr>
+    <td>{{ c.id }}</td>
+    <td>{{ c.char_name }}</td>
+    <td>{{ c.account_name }}</td>
+    <td>{{ c.level }}</td>
+    <td>{% if c.isgm %}<span class="badge ok">GM</span>{% endif %}</td>
+    <td>{% if c.isdev %}<span class="badge ok">Dev</span>{% endif %}</td>
+    <td class="row-actions"><a class="btn small" href="{{ url_for('edit_character', char_id=c.id) }}">bearbeiten</a></td>
+  </tr>
+  {% endfor %}
+</table>
+{% endblock %}