v2.1.0

• Message & chat cost. New cost_mode valve: auto (default) shows the provider's own reported cost only (OpenRouter usage.cost, LiteLLM, ...) and never fetches or guesses; estimate additionally approximates cost from models.dev prices (always marked ≈), with correct cached/reasoning and Anthropic cache-read/write pricing; off disables cost entirely. Shows the per-message cost (💰) and a running chat total (💰Σ) in USD.
• Optional live models.dev price fetch (api.json, exact per-provider prices, cached ~24h, on by default in estimate mode) with a built-in offline price table as fallback and a manual price_map override that always wins.
• debug_mode is now copyable in-chat: the stats line just gets a small (debug) marker, and the full diagnostic payload is attached as a "Token Usage & Cost Display - Debug info" source whose modal renders it as a JSON block with a Copy button and persists with the message (still mirrored to the server log). The previous status line was clamped to one line and couldn't be selected.
• Minimum lowered to Open WebUI 0.9.0 (was 0.10.0+): the data contracts the plugin relies on - per-message usage in the outlet (since 0.9.0) and normalized usage (since 0.8.0) - predate 0.10, so it runs on 0.9.x with graceful degradation; only provider-reported cost in auto mode needs 0.10.0+ (use estimate on older versions).
• debug_mode now writes the full payload to the server/container logs (copyable, never truncated) and shows only a short summary in the chat status line - the previous status-only output was clamped to one line and couldn't be selected.