KE's Test Task

[UnoYakshi]

Notes:

• the requirement were met (unless me being inattentive)
• there is TODO-list in TODO.md, i.e., much or less WIP
• there is .env file for SECRET_KEY, DEBUG_MODE, and PSQL credentials
• don't forget to pip install -r pip-reqs
• there is DB (PSQL) dump in YAML
• for price range task I've used admin_numeric_filter due to my laziness over creating a new form\template\whatever
• all feedback (Django-wise, Python-wise, architecture-wise, linguistics-wise, etc.) is welcomed
• Product-Shop relation was remade to Many-to-Many
• please, don't mind ... -- it's just my way of ending the sentence + kind of personal insignia
• haven't touched Django in 3 years or so, therefore I'd ask not to through too weighty rocks at me