Zest-First Dry Brine : Add lemon zest, half the garlic, oregano, thyme, paprika, pepper, and half the measured salt to a large bowl. Add the chicken thighs, toss to coat thoroughly, and let stand 10 to 15 minutes.
Bright Marinade : In a small bowl, whisk lemon juice, Dijon, extra-virgin olive oil, and the remaining garlic and salt until emulsified.
Gloss the Vegetables : On a parchment-lined sheet pan, toss zucchini, bell pepper, red onion, tomatoes, and chickpeas with 2 to 3 tablespoons of the marinade (just enough to lightly coat). Spread into an even layer.
Stage the Pan ; Nestle the chicken thighs on top of the vegetables, presentation side up, spacing them evenly.
Roast & Render : Roast at 425°F (220°C) for 20 minutes, until the vegetables begin to soften and the chicken edges look opaque.
Olives In, Baste & Continue : Scatter the olives over the pan. Spoon 1 to 2 tablespoons of the remaining marinade over the chicken and a few hot spots on the pan. Continue roasting 10 to 12 minutes more, until the chicken reaches 165°F (74°C) at the thickest part (avoid the bone).
Optional Color Boost : Broil for 1 to 2 minutes to deepen golden edges. Watch closely.
Finish & Serve : Remove from the oven, sprinkle with parsley and a light crumble of reduced-fat feta (if using). Spoon a little pan jus over each portion.