Landing: add the zeta ball video (From Riemann to zeta)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FAqjv3n4yABxvJPJHFRhVA

index.html

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   <h2 style="font-family:var(--display);font-weight:500;font-size:28px;margin:8px 0 0">Symmetry costs a line</h2>
   <p class="lede">Force up–down mirror symmetry on the yantra while keeping all 29 triple points exact, and two of its bases are pulled into one line, carrying one point on the axis and a mirror pair: 1 + 2.</p>
   <video controls playsinline preload="none" src="https://teahub.xyz/maths/videos/raw/commit/a7601b040a95725e40e58f6ac214a2fe096a3a3e/yantra-symmetry.mp4"></video>
-  <h2 style="font-family:var(--display);font-weight:500;font-size:28px;margin:8px 0 0">The same move on ζ</h2>
-  <p class="lede">Put ½ at the centre instead of the bindu. The critical line becomes the strut through 0 and ∞, the functional equation a sign flip through the centre. Swap ζ for a function with the same symmetry and no Euler product (Davenport–Heilbronn) and the zeros step off the strut: symmetry alone does not pin them, the arithmetic is the extra incidence.</p>
+  <h2 style="font-family:var(--display);font-weight:500;font-size:28px;margin:8px 0 0">From Riemann to ζ</h2>
+  <p class="lede">The plane is a ball with a lamp on top. Feed ζ a grid and it draws latitude and longitude of a globe lying on its side, poles over 0 and 1. The equator casts the critical line; its two ends are ½ and ∞; the functional equation is the half-turn that swaps the poles and keeps the equator. The Riemann hypothesis, on the ball: every zero lives on the equator, climbing toward the lamp.</p>
+  <video controls playsinline preload="none" src="https://teahub.xyz/maths/videos/raw/commit/09ce27644482fc035c25a2fb3861b8e9dd164c45/zeta-ball.mp4"></video>
+  <p class="lede">The same ball in two explorers: put ½ at the centre and the critical line becomes the strut through 0 and ∞, the functional equation a sign flip through the centre. Swap ζ for a function with the same symmetry and no Euler product (Davenport–Heilbronn) and the zeros step off the strut: symmetry alone does not pin them, the arithmetic is the extra incidence.</p>
   <div class="cards">
     <a class="card" href="strut/">
       <h2>The zeta strut</h2>