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>

.env.example

@@ -0,0 +1,18 @@
+# Flask Configuration
+FLASK_APP=run.py
+FLASK_ENV=development
+SECRET_KEY=change-this-to-a-random-secret-key-in-production
+
+# Claude API Configuration
+ANTHROPIC_API_KEY=your-claude-api-key-here
+
+# ClamAV Configuration
+CLAMD_SOCKET=/var/run/clamav/clamd.ctl
+
+# Application Configuration
+DATA_DIR=./data
+MAX_CONTENT_LENGTH=10485760
+
+# Rate Limiting
+RATE_LIMIT_ENABLED=true
+RATE_LIMIT_PER_HOUR=10