Is it okay to stay an extra day than my Schengen visa validity if I pass through immigration before midnight? [duplicate]

In your opening line you say you have a visa, but then later you ask about issues at the consulate. But basically the same answer applies if you are talking about the immigration official when you land or the consular official when you apply.

Officially your travel period is 11 days since your flight departs after midnight. But in real life terms you will have cleared immigration and left the country the day before (unless you are really running wayyyy late). It will lie with the judgement of the official handling your entry/visa application to decide to allow the leeway or apply the letter of the law.