Is there an NPC someplace in Fallout 3, or the expansions, who can repair the unique items (Chinese stealth armor, etc) to 100%?
According to the Fallout 3 Wiki -- Somah (An NPC from the Mothership Zeta DLC) has a repair skill of 100.
You may also look into Haley (An NPC from the Point Lookout DLC) who has a glitch that will eventually bring his repair skill up to 100.
If you are just looking to repair your unique items up to 100%, look into Alien Epoxy, a semi-repeatably obtainable consumable that instantly restores between 15% and 30% condition to an item. (Also from the Mothership Zeta DLC)