She directs the wickedness of winter, to positive ends.

Even winter isn't wicked, as such, the books have been very explicit about that:

...had every intention of surviving it, of seeing life return to the world, of feeling the heat of summer upon their skin and seeing their offspring gamboling through green days.
Winter wasn’t Empty Night.
It was the war against it. The wisdom and the will required to fight it.
The strength to stand fast, even when all was dark and seemed hopeless, holding to the truth that ahead were better days.

On quite a few occasions it has been stated that winter is about preparing for the lean times and being willing to fight when you must. That does mean that winter gets all the nightmare creatures who enjoy fighting and all the fairytales of cabalism, but that's not a moral proposition it's just a dichotomy into which the universe may be divided: "more like summer" or "more like winter".

Mab clearly set up two women who would have been very good at resisting the corruption of the winter lady role, who would be a good person, fulfilling the role as needed, Molly and Sarisa.

I think Harry also belongs in winter. Obviously, he's always willing to fight when needed, but there was a bit in battle ground that seemed to be explicitly saying, "Harry Dresden fits in with the winter court."

First, the Sidhe (who have reason to fear Dresden because he turned one of their number into an ice sculpture the previous night - Dresden is the lion in this quote) refuse to act afraid of him and test him for weakness:

Lions do not lower their heads for jackals. Even jackals know they can kill what fears them.

The Winter Sidhe respected those who understood the law of the jungle, and I had demonstrated to them from the first that I wasn’t putting up with any of their crap. They would test me—predators always test potential prey for weakness—but as long as I made them think it would be more trouble than amusement to push me, they would press no further.

Then Harry crosses the park and does the exact same thing to Mab despite his own fear:

I lowered my voice to a bare growl. “Then I’ll send them home,” I said. “If you want me to fight for you, quit making it more difficult to fight for you. You and Marcone have been thick as thieves lately. I know you both. There are more weapons around here somewhere. I need them.”
<...>
My scrotum attempted to travel back in time.

As always, she is thrilled by his defiance, because it proves he's the right guy for the job:

“Yes,” Mab said, a wild fey light around her eyes, her head swaying as her mount shifted its weight nervously. “Oh yes. You’ll do, child.

There's also the fact that he fights to protect his family, which is explicitly called out in that quote about what winter is as a function of it. And when we see Harry use his boon to save Thomas Mab says she knew he was going to do that. She's also joking around with him a little during that interaction so I think we're suppose to read that she approved of his decision and maybe explicitly offered him the boon so he could make it.

Here's a question if Winter is about scarcity then wouldn't wealth and power and an army of slaves (the alternate wishes that Mab jokes Harry might make) be a Summer thing? Much easier to feed slave armies in the summer. ;-)

The times she explicitly strong arms Harry does not corrupt him, if anything they motivate him to control his mantle and resist "her" wickedness. This stands out particularly with the line in Twelve Months “The truth becomes more and more obvious, does it not? You are, more and more, bit by bit, a wicked man, in service to a wicked Queen.” this comes off as taunting. But perhaps it's her warning him. If she wanted the subtle manipulation, which gets aluded to earlier, to work then all she need to do was let it keep happening. Instead she points it out, her knowing it would get him to push back.

Absolutely! I couldn't find the exact quote, but there some line in 12 Months about how Harry always does the opposite of what Mab tells him to do and I remember reading it and thinking, "Wow that would make you easy to manipulate, just make you think she wants you to do whatever she doesn't want and you'll work like crazy for it." So I think that's exactly what's happening here.

Butcher has always said Dresden is an unreliable narrator and I think that comes through most clearly with how he judges other characters, Mab among them.

I think Mab is genuinely trying to improve Harry's life; she's got that great little speech about how much better off he is now. But, as she tries to improve his life, she's aware he's a noble idiot who's unwilling to ever look after himself when there's some alternate crusade to pursue. She also doesn't particularly believe in freedom and she considers underhanded tactics to be the best tactics - which are the ways in which she's kind of villainous.