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/edit_account.html

@@ -0,0 +1,33 @@
+{% extends "base.html" %}
+{% block title %}{{ account.username }} - ROSS Admin{% endblock %}
+{% block content %}
+<div class="card" style="max-width:480px;">
+  <h2 style="margin-top:0;">Account: {{ account.username }}</h2>
+  <form method="post">
+    <label>Accesslevel (100 = normaler Spieler, 900 = Admin)</label>
+    <input type="number" name="accesslevel" value="{{ account.accesslevel }}">
+    <label><input type="checkbox" name="active" style="width:auto;" {% if account.active %}checked{% endif %}> Aktiv</label>
+    <label>Neues Passwort (leer lassen = unverändert)</label>
+    <input type="password" name="password" placeholder="unverändert">
+    <div style="margin-top:20px;">
+      <button type="submit">Speichern</button>
+      <a class="btn secondary" href="{{ url_for('accounts') }}">Zurück</a>
+    </div>
+  </form>
+</div>
+<div class="card">
+  <h3 style="margin-top:0;">Charaktere auf diesem Account</h3>
+  <table>
+    <tr><th>Name</th><th>Level</th><th></th></tr>
+    {% for c in chars %}
+    <tr>
+      <td>{{ c.char_name }}</td>
+      <td>{{ c.level }}</td>
+      <td><a class="btn small" href="{{ url_for('edit_character', char_id=c.id) }}">bearbeiten</a></td>
+    </tr>
+    {% else %}
+    <tr><td colspan="3">Keine Charaktere.</td></tr>
+    {% endfor %}
+  </table>
+</div>
+{% endblock %}