It would be interesting to know whether any Jewish interpreters in the past interpreted it as a statement rather than a question, in the way that the great Protestant Bible translators did, Wycliffe (1300s), Luther (1500s), etc etc.
I see it this way. These psalms from 120 to 134 are "songs of degrees" (KJV) or ascents, songs sung as the annual pilgrims went up to Jerusalem, to Zion (the fortress) and Moriah (the temple) - though the name Zion seems to have been transferred from one to the other. As the OP points out, there are many verses where God is said to be in Zion, or in his holy temple. And in another of the songs of degrees, Psalm 128, it specifically says "The Lord shall bless thee out of Zion"; another song of degrees, Psalm 134, says "The LORD that made heaven and earth bless thee out of Zion."
There is no contradiction between God blessing out of his earthly dwelling place, the place where he is worshipped, and blessing out of heaven. See for instance Psalm 11:4."The LORD is in his holy temple, the LORD'S throne is in heaven: his eyes behold, his eyelids try, the children of men.", and it's worth looking at all the other references to "holy temple" and "holy hill" for instance at blueletterbible.org - here's another "I cried unto the LORD with my voice, and he heard me out of his holy hill."
So I am very curious as to whether any of the earlier Jewish interpreters took it this way. Can we tell, for instance, whether the Septuagint (ἦρα τοὺς ὀφθαλμούς μου εἰς τὰ ὄρη πόθεν ἥξει ἡ βοήθειά μου) interprets it as a question, or can it be read either way?