Search Query Performance tracker

Read https://www.sellermate.ai/api-docs first. It documents the SellerMate Public API: REST over HTTPS, X-API-Key auth, and every tool with its parameters is on that page. Every tool is POST https://api.sellermate.ai/public/v1/tools/{name} with a JSON body.

Build me a Search Query Performance tracker for one account.

Each month:
- Pull last month's SQP data with get_sqp_report (it takes integer month and year, not dates)
- For the top [50] queries by total impressions, record impression share, click share, cart-add share and purchase share for my brand
- Append a row per query per month to sqp-history.csv
- Print the 10 queries where purchase share moved most versus the previous month, up and down
- Pull the same ASINs' sessions and conversion from get_retail_product_performance and add them to the output

Resolve the account with get_user_context.

Rules:
- My key is in the SELLERMATE_API_KEY environment variable. Send it as the X-API-Key header. Never hard-code it or log it.
- Call get_user_context first and use the accounts it returns. Don't invent account ids.
- Report tools are paginated (page, page_size up to 500, pagination.hasMore). Walk every page.
- On a 429, wait for the Retry-After header and retry. On a 401 or 403, stop and tell me.
- Show me the plan and the code before running anything that writes.

Stack: Python 3 with requests and the csv module.