chore: 404 -> NOT_FOUND + http transport tidy-ups

Armaan Guptarequested to merge
chore/error-and-http-cleanup into develop

Closes #15 (closed) .

  • cdliFetch / cdliFetchWithHeaders map 404 to ErrorCode.NOT_FOUND (non-retryable); cdliFetchText already treats 404 as a normal outcome, left as-is.
  • type index-http's server as node:http Server.
  • 405 handlers use res.status().json() so the body sets Content-Type.

No new behavior beyond the error code. Verified: lint + build clean; nonexistent id -> NOT_FOUND; GET/DELETE /mcp -> 405 with Content-Type: application/json.

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