Daplug 0.40.15 — Gemini 4 Argon

Adds argon/argon-high (High), argon-medium, and argon-low via verified Antigravity catalog tiers. Existing Gemini defaults are unchanged. Argon is AGY-only; unverified CLI overrides are rejected. Includes generated menus, discovery inventory, routing regression coverage, a passing full local release gate, and a successful live Argon Low terminal-tool smoke test.