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>

server.js

@@ -37,6 +37,7 @@ FACTS:
 - Strategy: enter RM Circle dApp at Premium tier (${c.premiumEntryPol || 362} POL on Polygon Mainnet, chain ID 137, POL is the gas token). Each member gets EXACTLY 2 directs, then the position is "qualified" and its referral link is retired. The team then helps those 2 get their 2 (moving-link strategy). Build depth, not width. Never add extra directs to a qualified link.
 - First team goal: 30 properly placed positions (2+4+8+16), then 32, 64, 128 and beyond.
 - 8 Premium levels in order: Scintilla, Ascensus, Fabrica, Culmen, Apex, Fastigium, Vertex, Corona. Everyone starts at Scintilla. Upgrade as quickly as practical, ideally with earned POL; the first two payments at each level help fund the next upgrade. Stay aware of your active downline's levels so you don't fall behind and miss payments.
+- SPILLOVER: when a sponsor's two matrix slots are full, the contract places new members in the next open slot further down (left to right) — possibly under someone else. Spillover fills that member's matrix and sets up future upgrade income to their position, but does NOT count toward qualification: only people who join using a member's own ID are their directs. Upgrade payments travel up the MATRIX (not who-referred-whom) and only stop at positions that are qualified (2 directs) AND already at the level being bought — otherwise the payment passes them by to the next eligible upline. Members can see their own matrix, spillover tags, and payments at https://rmcircle.saasy.top/my
 - Current team sponsor: ${a ? `ID ${a.id}${c.showSponsorName && a.name ? ` (${a.name})` : ''}, ${a.directs}/2 directs` : 'shown on the start page'}. ${waiting} placement(s) waiting. Placements rotate as positions qualify — always verify on https://rmcircle.saasy.top/start right before joining.
 - Site pages: https://rmcircle.saasy.top/ (strategy overview + roadmap), https://rmcircle.saasy.top/start (current sponsor + join steps), https://rmcircle.saasy.top/training (4 videos: 1. How the team build works, 2. Create your MetaMask wallet, 3. Funding your wallet, 4. Buying the Premium position).
 - Telegram group for live team help: ${c.telegramUrl || 'https://t.me/cryptoteambuild'}