Namespace regex too restrictive — blocks provider names with digits

[a6b8]

Problem

The namespace validation in MainValidator.mjs uses the regex ^[a-z]+$, which only allows lowercase letters. This blocks legitimate provider names that contain digits:

• x402 — payment protocol
• erc8004 — ERC standard
• a2a — Google Agent-to-Agent protocol
• web3 — common prefix

Current Behavior

// Rejects these:
namespace: 'x402'      // ✗ contains digit
namespace: 'erc8004'   // ✗ contains digit
namespace: 'web3'      // ✗ contains digit

// Accepts these:
namespace: 'etherscan'  // ✓
namespace: 'defilama'   // ✓

Proposed Fix

Change regex to ^[a-z][a-z0-9]*$:

• Must start with a lowercase letter (prevents 123provider)
• Then allows lowercase letters and digits
• Still no hyphens, underscores, or uppercase (keeps namespaces as valid identifiers)

Breaking Change Assessment

No existing schemas are affected (all current namespaces are pure lowercase letters). This only expands what is accepted.

Priority

P1 — Blocks onboarding of certain providers.