fix(core): should not suggest when minSimularity set to 1

[Hieuzest]

当前缀非空、启用严格前缀模式、模糊系数为1时，在私聊\指向性场景使用无前缀指令仍然会触发suggest

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.10%. Comparing base (5c370ac) to head (a4fb977).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1508   +/-   ##
=======================================
  Coverage   87.10%   87.10%           
=======================================
  Files          36       36           
  Lines        5552     5552           
  Branches     1067     1066    -1     
=======================================
  Hits         4836     4836           
  Misses        716      716           

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