feat: Phase 3 — web dashboard, testing, and CI/CD

- Remove multi-marketplace from Phase 3
- Add FastAPI web UI on port 8766 with basic auth
- Add 6 Jinja2 templates (dashboard, keywords, users, ads, stats)
- Add pytest test suite (45 tests, 49% coverage)
- Add GitHub Actions CI/CD workflow
- Update docker-compose.yml to expose web UI port
- Update Dockerfile to include tests

worker/src/templates/users.html

@@ -0,0 +1,66 @@
+{% extends "base.html" %}
+{% block title %}Users — Willhaben Tracker{% endblock %}
+{% block content %}
+<div class="page-header">
+    <h2>Users</h2>
+</div>
+
+{% if not error and users %}
+<div class="card" style="overflow-x: auto;">
+    <table>
+        <thead>
+            <tr>
+                <th>Telegram ID</th>
+                <th>Username</th>
+                <th>First Name</th>
+                <th>Admin</th>
+                <th>Status</th>
+                <th>Mute Hours</th>
+                <th>Digest Mode</th>
+                <th>Digest Interval</th>
+            </tr>
+        </thead>
+        <tbody>
+            {% for user in users %}
+            <tr>
+                <td>{{ user.telegram_id }}</td>
+                <td>@{{ user.username }}{% if not user.username %}—{% endif %}</td>
+                <td>{{ user.first_name or '—' }}</td>
+                <td>
+                    {% if user.is_admin %}
+                    <span class="badge badge-yellow">Admin</span>
+                    {% else %}
+                    <span class="badge" style="background: #555; color: #fff;">User</span>
+                    {% endif %}
+                </td>
+                <td>
+                    {% if user.is_active %}
+                    <span class="badge badge-green">Active</span>
+                    {% else %}
+                    <span class="badge badge-red">Inactive</span>
+                    {% endif %}
+                </td>
+                <td>
+                    {% if user.mute_start and user.mute_end %}
+                    {{ user.mute_start.strftime('%H:%M') }} — {{ user.mute_end.strftime('%H:%M') }}
+                    {% else %}
+                    —
+                    {% endif %}
+                </td>
+                <td>
+                    {% if user.digest_mode %}
+                    <span class="badge badge-green">On</span>
+                    {% else %}
+                    <span class="badge" style="background: #555; color: #fff;">Off</span>
+                    {% endif %}
+                </td>
+                <td>{{ user.digest_interval }}m</td>
+            </tr>
+            {% endfor %}
+        </tbody>
+    </table>
+</div>
+{% elif not error %}
+<div class="card"><em>No users found.</em></div>
+{% endif %}
+{% endblock %}