reports: add PDF generation infra (fpdf2); Phone Book CSV/PDF export; Payments - Detailed report with preview and PDF grouped by deposit date; update Dockerfile for deps; smoke-tested in Docker

Dockerfile

@@ -8,6 +8,8 @@ WORKDIR /app
 RUN apt-get update && apt-get install -y \
     gcc \
     curl \
+    libjpeg62-turbo \
+    libfreetype6 \
     && rm -rf /var/lib/apt/lists/*
 
 # Copy requirements first for better layer caching