I think there are some Hadith in this book are not compatible with Quran.

Also I think this is not a logic term to say "Sahih Bukhari is Sahih (authentic) because its name is Sahih"

Bukhari was an Iranian written this book near 200 years after prophet and indeed any human can have mistakes.

Also Jamal Albanna a sunni Scholar argues that

653 of the hadiths as written in al-Bukhari and Muslim are incorrect and should not be accepted.

His Arabic book is titled "The Cleansing of Bukhari and Muslim from useless Hadiths" (2008).

Firstly I want to know considering Sahih Bukhari a 100% authentic Book by sunni scholars is true or not? and if yes is it an Islamic fitwa or it is mostly for policies of Sunni Kings during history and accepted as a rule today? or has other reason?

Here is an article but in Persian containing names of many sunni scholars with evidence critiquing Sahih Bukhari and not considering in 100% authentic:

http://hawzah.org/FA/articleview.html?ArticleID=79418

translating all of it takes much time. and maybe you can read it using google translator.

for example this article says Ibn Hajar Asqalani in his book Tahzib al-Tahzib volume 10 page 461 (تهذیب التهذیب، ج 10، ص 461) says there are some narrators in Sahih Bukhari that Muslim never consider them reliable and even critiqued them and did not narrate any hadith from them. for example one narrator Muslim never considered him reliable is نعیم بن حماد مروزی. some sunni scholars considered him reliable but still many not. I think evidences from sunni books mentioned in this article prove there is no Ijma among sunni scholars that Sahih Bukhari is 100% authentic.