Cook linguine in a large pot of boiling salted water, stirring occasionally, until al dente. Drain, reserving 1 cup pasta cooking liquid.
Meanwhile, heat 2 Tbls olive oil in a large skillet over medium-high. Add panko, season with kosher salt, and cook, stirring often, until golden brown and crisp, about 3 minutes. Transfer to a small bowl. Wipe out skillet.
Heat 2 Tbls olive oil in same skillet over medium-high. Add calamari, drained and patted dry, and cook, tossing occasionally, until golden brown and crisp, 2–3 minutes. Using a slotted spoon, transfer to a plate.
Add remaining 1 Tbls olive oil to same skillet. Cook garlic cloves, coarsely chopped and coarsely chopped drained capers, stirring often, until slightly softened, about 2 minutes. Add crushed red peppersand a big pinch of salt; season generously with freshly ground black pepper. Cook, stirring constantly, until combined and fragrant, about 1 minute. Add white wine and cook, stirring often, until reduced by two thirds, about 4 minutes.
Add pasta, parsley, butter and reserved ½ cup pasta cooking liquid to skillet; reduce heat to medium-low. Cook, tossing often and adding remaining pasta cooking liquid a little at a time as needed, until pasta is coated. Remove from heat.
Add calamari, then finely grate zest from lemon over. Squeeze in juice from 1 half lemon and toss to combine. Cut remaining half into wedges.
Divide pasta among shallow bowls and top with panko mixture. Serve with lemon wedges for squeezing over.