feat: dashboard web FastAPI Sprint 4

Ajout d'un dashboard lecture seule par-dessus la DB SQLite existante.

Fichiers créés :
  - tickettracker/web/queries.py   : 7 fonctions SQL (stats, compare, historique...)
  - tickettracker/web/api.py       : router /api/* JSON (FastAPI)
  - tickettracker/web/app.py       : routes HTML + Jinja2 + point d'entrée uvicorn
  - tickettracker/web/templates/   : base.html, index.html, compare.html, product.html, receipt.html
  - tickettracker/web/static/style.css : personnalisations Pico CSS
  - tests/test_web.py              : 19 tests (96 passent, 1 xfail OCR)

Fichiers modifiés :
  - requirements.txt : +fastapi, uvicorn[standard], jinja2, python-multipart, httpx
  - config.py        : +DB_PATH (lu depuis TICKETTRACKER_DB_PATH)

Lancement : python -m tickettracker.web.app

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tickettracker/web/templates/index.html

@@ -0,0 +1,104 @@
+{% extends "base.html" %}
+
+{% block title %}Accueil — TicketTracker{% endblock %}
+
+{% block content %}
+<h1>Tableau de bord</h1>
+
+{% if empty %}
+<article>
+    <p>
+        Aucun ticket importé. Utilisez la CLI pour importer vos tickets :
+    </p>
+    <pre><code>python -m tickettracker.cli import chemin/vers/ticket.html  # Picnic
+python -m tickettracker.cli import chemin/vers/ticket.pdf   # Leclerc</code></pre>
+</article>
+{% else %}
+
+<!-- Cartes de statistiques -->
+<div class="stat-grid">
+    <article class="stat-card">
+        <h3>{{ stats.total_receipts }}</h3>
+        <p>Tickets importés</p>
+    </article>
+    <article class="stat-card">
+        <h3>{{ "%.2f"|format(stats.total_spent) }} €</h3>
+        <p>Total dépensé</p>
+    </article>
+    <article class="stat-card">
+        <h3>{{ stats.distinct_products }}</h3>
+        <p>Produits distincts</p>
+    </article>
+    <article class="stat-card">
+        <h3>{{ stats.total_items }}</h3>
+        <p>Articles scannés</p>
+    </article>
+</div>
+
+<!-- Graphique dépenses par mois -->
+<article>
+    <h2>Dépenses par mois</h2>
+    <div class="chart-container">
+        <canvas id="monthlyChart"></canvas>
+    </div>
+</article>
+
+<script>
+(function () {
+    const data = {{ chart_data | tojson }};
+    const ctx = document.getElementById("monthlyChart").getContext("2d");
+    new Chart(ctx, {
+        type: "bar",
+        data: data,
+        options: {
+            responsive: true,
+            plugins: {
+                legend: { position: "top" }
+            },
+            scales: {
+                x: { stacked: true },
+                y: {
+                    stacked: true,
+                    ticks: {
+                        callback: function(value) { return value + " €"; }
+                    }
+                }
+            }
+        }
+    });
+})();
+</script>
+
+<!-- Tableau des derniers tickets -->
+<article>
+    <h2>Derniers tickets</h2>
+    <div class="overflow-auto">
+        <table>
+            <thead>
+                <tr>
+                    <th>#</th>
+                    <th>Enseigne</th>
+                    <th>Date</th>
+                    <th>Total</th>
+                    <th>Articles</th>
+                    <th></th>
+                </tr>
+            </thead>
+            <tbody>
+                {% for r in receipts %}
+                <tr>
+                    <td>{{ r.id }}</td>
+                    <td>{{ r.store }}</td>
+                    <td>{{ r.date }}</td>
+                    <td>{{ "%.2f"|format(r.total) }} €</td>
+                    <td>{{ r.nb_items }}</td>
+                    <td><a href="/receipt/{{ r.id }}">Voir</a></td>
+                </tr>
+                {% endfor %}
+            </tbody>
+        </table>
+    </div>
+</article>
+
+{% endif %}
+{% endblock %}