Clean the squid as described here. Slice the bodies lengthwise into 1/4-inch strips. Put the strips and the cleaned tentacles into separate bowls and season each evenly with salt, pepper, chile flakes, and 2 tablespoons of the oil. Set aside.
Smash the garlic and a pinch of salt into a paste following the directions in the sidebar at right. Whisk the garlic with 1/2 cup of the olive oil in a small bowl. Season well with salt and pepper.
Bring 1 quart of salted water to a boil in a medium saucepan. Add the zucchini and cook until just tender, 3 to 4 minutes. Use a slotted spoon to transfer the zucchini to a plate to cool. Sprinkle with salt and drizzle with 1 tablespoon olive oil.
In the same pot of boiling water, cook the squid strips until they become just firm to the tooth, about 1 minute. Transfer with a slotted spoon to a large plate to cool. Cook the tentacles the same way but for about 90 seconds; drain and add to the strips. Sprinkle with salt and drizzle on one-quarter of the lemon juice and the remaining 1 tablespoon olive oil.
In a large, shallow bowl, combine the chickpeas, zucchini, and calamari. Drain the soaking onions, dry briefly on paper towels, and add to the chickpeas. Add the garlic oil, the remaining lemon juice, the parsley, and the basil and toss. Taste for salt and pepper.
Let the salad marinate for 1 hour at room temperature before serving. You can also refrigerate the salad for up to a day ahead, but make sure it comes to room temperature before serving and taste for salt, pepper, lemon, and chile flakes.