feed: more reasonable structure for rescraping: static-map sampling

[zhehaowang]

one way to facilitate market data study is to instead of rescraping all each time we run a scraper, keep the thing running all the time.
When we get a quote we schedule an event one day later to get another get request for the same item one day later.

A few advantages of this way:

• facilitate market data study
• fewer botched run clean-ups
• pushes for / could benefit from a db-based storage
• if done right, maybe could help with stockx perimeterx situation?
• helps with combining everything into a single (more or less 'idempotent') decision making unit

Static mapping (url we identified from each site that we would care about) could be scraped at a lower frequency. Each time we start we start by sending requests to those we have missed that last mark on, and works on scheduled events from there.

This unfortunately requires an overhaul of the current system.
We should also consider the system more carefully with this.

[zhehaowang]

feed v2 was an overhaul of feed in favor of this approach: build a static mapping (cross reference from multiple sources) rarely.
For each item in the static mapping, retrieve price snapshot and transaction history daily from all sources.
Strategy reads the daily scraped data and makes recommendations.