Auto-sell: automatic removal of listings that stay online too long.

• New setting "Remove listings after": duration X with a minutes/hours unit (1 minute to 30 days), can be disabled, and is kept between sessions.
• While auto-sell is running, an extension-created listing older than X is removed: the listing slot is freed and the card, with its exact quantity, returns to the inventory and the available-card pool.
• The card gets the internal "returned after expiry" status and is placed at the very end of the ranking, ordered by removal time. A 10-minute anti-loop delay prevents immediate reselection; once relisted, its timer starts from zero.
• Manual listings and already-completed sales are never touched: the real listing state is re-read right before each removal, with a lock against double removal.
• UI: elapsed time since listing, removal deadline, timestamped notice and persistent log of removals and relistings.

Tests: 81 unit checks (test/verify-autosell-expiry.mjs) + 97 end-to-end Chrome checks (test/chrome-smoke.mjs), web-ext lint with 0 errors.
Commit: https://github.com/mRNeFF/kyareeh-plus/commit/c14a2e4