only activate minuet blink provider if key is set

lua/plugins/blink.lua

@@ -73,6 +73,7 @@ return {
           -- since minuet.config.request_timeout is in seconds
           timeout_ms = 3000,
           score_offset = 50, -- Gives minuet higher priority among suggestions
+          enabled = vim.env.GEMINI_API_KEY ~= nil,
         },
       },
     },