Add a query object that returns inventory level snapshots (active count over time) per market segment.
Pulls from `listing_snapshots` since that's the append-only history. `PriceTrendQuery` is the closest existing pattern.
Likely signature:
```ruby
InventoryLevelsQuery.new(zip_code:, months: 12).call
=> [{ month:, active_count:, sold_count:, new_listings: }, ...]
```
Add a query object that returns inventory level snapshots (active count over time) per market segment.
Pulls from `listing_snapshots` since that's the append-only history. `PriceTrendQuery` is the closest existing pattern.
Likely signature:
```ruby
InventoryLevelsQuery.new(zip_code:, months: 12).call
=> [{ month:, active_count:, sold_count:, new_listings: }, ...]
```