Add actionability gate (visible + stable + enabled + not-occluded)

[JE-Chen]

Playwright/Cypress/WebdriverIO run an actionability check before every click — present + stopped moving + enabled + not covered. AutoControl had none: self_heal_click locates and clicks immediately, wait_until_screen_stable watches only the whole frame.

• wait_actionable (AC_wait_actionable): composes the four checks into one gate, returning an ActionabilityReport (per-check booleans, target point, waited_s, and reason = the first failing check).
• act_when_ready: waits then calls action(center_point), raising AutoControlActionException on timeout.
• Every signal is an injectable callable (bbox_provider / region_sampler for pixel-stability / enabled_probe / hit_tester) plus an injectable clock/sleep via GateConfig, so the gate is fully deterministic and headless-testable (fake clock advances only on sleep). The executor command binds the gate to a template image located each poll + region pixel-stability.
• Wired through all 5 layers + headless test + EN/Zh docs + WHATS_NEW. Qt-free.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud