Verify YM C304 terminal-entry tail stability

[stevemoraco]

Public guarded theorem-equivalent replay for RH-Lean C304.

Formalized scope only:

• the printed condition C * eps <= eps / 2 forces C <= 1/2 when eps>0;
• a finite one-step forcing budget can eject the recurrence from an arbitrarily small target ball;
• after independent entry into a radius-r ball, C r <= 1/2 plus C delta_k <= r/2 keeps the quadratic recurrence inside the ball.

This does not formalize the Yang-Mills RG, terminal entry, Eq. 7.19, AF/IR identification, continuum OS reconstruction, a mass gap, or the Clay theorem.

FIVE-ALARM OFF.