Fifth parity tier (first half): three more controls. DatePicker and Form/Section are deferred to a follow-up.

What's new

• Stepper — Stepper(_:value:in:step:) clamps a Strideable binding to a range (plus the onIncrement/onDecrement closure form); the interpreter renders the label with − / + buttons.
• SecureField — shares the TextField node with a secure flag; the interpreter applies a PasswordVisualTransformation.
• Menu — a trigger button opening a Compose DropdownMenu; each child Button becomes an item firing its own tap callback.

Verification

• swift test — 3 new tests (Stepper increments/decrements and updates its label; SecureField emits a secure node; Menu emits label + items), 47 total passing
• Emulator (new More Controls screen): stepper counts up/down, secure field obscures input while reporting length, menu opens and the picked action lands ("Chose: Delete")

Deferred

DatePicker, Form/Section (next tier). Stepper has no long-press auto-repeat.