ecosystem: add dex-data (multi-chain DEX market data over x402)

[donnywin85]

Adds dex-data to the ecosystem page under Services/Endpoints.

Live multi-chain DEX market data behind an x402 paywall: USD price for any
ERC-20 by ticker or contract address, per-venue liquidity depth, raw pool
reserves, best execution venue, liquidity-risk depth class, and pre-trade price
impact for a specific trade size — across BNB Chain, Polygon, Arbitrum, Base and
Avalanche.

• 30 paid routes, all listed in the CDP Bazaar under
  payTo=0x2740651e046c59aB2A6510401140643292d3a96F
• x402 V2, USDC on Base, CDP facilitator
• Free tier requires no wallet, so an agent can evaluate before paying
• https://x402.donnyautomation.com/llms.txt documents the free and paid routes
• MCP server: npx -y github:donnywin85/dex-data-mcp

Followed the instructions in typescript/site/README.md: metadata under
app/ecosystem/partners-data/dex-data/, logo added to public/logos/ as SVG
(39 existing entries use SVG). metadata.json validated as parseable and the
category matches one of the four documented values.

[cb-heimdall]

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