Add atomic signal selectors to Kea

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What this task asks for

Introduce fine-grained atomic selector tracking with dependency health, circular detection, and unchanged Kea lifecycle behavior. Propagation: Support multi-level selector chains where updates propagate only to affected selectors. If a selector's inputs haven't changed, it should not re-evaluate. Circular Safety: Detect and prevent circular dependency loops **during the logic mounting/building phase**. When a loop is detected, the engine must throw an error containing the exact string: `[KEA] Circular dependency detected`. Compatibility: Ensure all baseline Kea behaviors (lifecycle events, mounting order) remain unchanged. The new engine intercepts core lifecycle hooks; valid implementations must ensure that standard plugin event ordering (e.g., `afterMount`) is not disrupted. React Integration: Components must re-render only when their accessed state or derived selectors change. Unrelated state updates must not trigger re-renders. When `atomicSelectors` is true, expose `logic.selectorHealth()` as a function. When disabled, `logic.selectorHealth` must be `undefined`.