Implement MVP: Anonymous feedback submission (User Story 1)

Complete implementation of Phase 1-3 (64 tasks):
- Phase 1: Project setup with Flask, pytest, configuration
- Phase 2: Core infrastructure (auth, models, services, testing)
- Phase 3: Anonymous feedback submission with file uploads

Features:
- Anonymous feedback submission (text and/or up to 3 file attachments)
- Multi-language support (any language accepted)
- File validation (type, size) and virus scanning (ClamAV)
- Product management with active/archived status
- File-based storage with YAML metadata
- User authentication system (Flask-Login)
- CSRF protection and rate limiting
- Test coverage: 10 passing tests (contract + integration)

Security:
- No IP address logging (FR-055 compliance)
- File type whitelist and size limits (10MB max)
- Virus scanning with graceful degradation
- Filename sanitization and secure storage

Test Results:
- 8 contract tests passed
- 2 integration tests passed
- End-to-end workflow verified

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/routes/auth.py

@@ -0,0 +1,48 @@
+"""Authentication routes"""
+from flask import Blueprint, render_template, request, redirect, url_for, flash
+from flask_login import login_user, logout_user, login_required
+from app.models.user import User
+
+
+bp = Blueprint('auth', __name__, url_prefix='/auth')
+
+
+@bp.route('/login', methods=['GET', 'POST'])
+def login():
+    """User login page
+
+    GET: Display login form
+    POST: Process login credentials
+    """
+    if request.method == 'POST':
+        username = request.form.get('username', '').strip()
+        password = request.form.get('password', '')
+
+        if not username or not password:
+            flash('Please provide both username and password', 'error')
+            return render_template('auth/login.html')
+
+        user = User.get_by_username(username)
+
+        if user and user.is_active and user.check_password(password):
+            login_user(user)
+            flash(f'Welcome back, {user.username}!', 'success')
+
+            # Redirect based on role
+            if user.role == 'administrator':
+                return redirect(url_for('admin.dashboard'))
+            elif user.role == 'product_owner':
+                return redirect(url_for('dashboard.list'))
+        else:
+            flash('Invalid username or password', 'error')
+
+    return render_template('auth/login.html')
+
+
+@bp.route('/logout')
+@login_required
+def logout():
+    """User logout"""
+    logout_user()
+    flash('You have been logged out', 'info')
+    return redirect(url_for('submission.form'))