Necessity is the mother of invention, as they say. I needed a tool that was small enough to lift the seedling from its small cell, but large enough to keep and hold an adequate ball of soil to protect the seedling's tender root. A silver pickle fork looked like it would be the perfect tool for the job ...
... and it was! Using the fork, I carefully lifted the seedling out of the corner of the cell, and it came out perfectly! (There is another seed in this cell, so I had to lift just the seedling and not disturb the rest of the cell.)
Downstairs in my basement workshop, I put a small amount of potting mix into a bowl, added some water, and stirred it up (using the pickle fork for this, too) ...
... filled a 3-inch pot with the mix, and hollowed out a hole about the size of the little seedling's root ball ...
... and used the fork to gently place the seedling into the hole. I used the tip my finger to firm the mix lightly around the rootball, and then gently watered the pot to settle the seedling into its new home.
Now the pot is under the grow light, keeping company with some of my rose cuttings from the fall.
More news on this as leaves form and especially (fingers crossed) when/if we get a bud and a flower.