Teach spillover in the chatbot and training page

- Chat: new canned answer covering spillover keywords (why "2 under me
  but 1/2 directs", pass-over eligibility) and the same facts added to
  the AI system prompt so both chat modes answer consistently.
- Training: "Understanding spillover" article after the videos — what it
  is, why it doesn't qualify you, why it still pays your position via
  matrix upgrade payments, and the qualified+leveled eligibility rule.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

public/chat.js

@@ -28,6 +28,8 @@
      a:()=>{const s=sponsorInfo&&sponsorInfo.sponsor;return s?`The current team sponsor is <strong>ID ${esc(s.id)}${s.name?' ('+esc(s.name)+')':''}</strong> — always verify on the <a href="/start">Getting Started page</a> right before you join, because placements rotate as positions qualify. Don't use an old screenshot or saved link.`:`The current sponsor is always shown live on the <a href="/start">Getting Started page</a> — check there right before joining, because placements rotate as positions qualify.`}},
     {k:['qualified','qualification','2 directs','two directs','directs','retire'],
      a:()=>`A position is <strong>qualified</strong> once it has exactly 2 directs. At that point we retire its referral link — no more directs on it — and shift the team's recruiting to its two positions below. That's what keeps the build growing in depth.`},
+    {k:['spillover','spill over','spill','under me but not qualified','people under me','not my direct','passed over','missed payment','skipped','why am i not qualified'],
+     a:()=>`<strong>Spillover</strong> happens when someone's sponsor already has both matrix slots full — the smart contract then places the new member in the next open slot further down, which can be under YOU. Spillover fills your matrix and sets up future upgrade payments to your position, but it does <strong>not</strong> count toward your qualification: only people who join using <em>your</em> ID are your directs. That's why you can see 2 under you and still show 1/2. And important: upgrade payments only stop at positions that are qualified (2 directs) AND at the required level — otherwise the payment passes you by to the next eligible upline. Check your position on your <a href="/my">Member Dashboard</a> — spillover placements are tagged there.`},
     {k:['level','levels','upgrade','scintilla','ascensus','fabrica','culmen','apex','fastigium','vertex','corona','8 levels'],
      a:()=>`There are 8 Premium levels: <strong>Scintilla, Ascensus, Fabrica, Culmen, Apex, Fastigium, Vertex, Corona</strong>. Everyone starts at Scintilla. Upgrade as quickly as practical — ideally using earned POL — because the first two payments at each level are designed to help fund your next upgrade. Stay aware of your active downline's levels so you don't fall behind.`},
     {k:['30 positions','goal','milestone','matrix','how many people','team size'],