docs: add EXAMPLES.md with worked evaluator type examples

Four complete examples covering under-documented evaluator types and
evaluation patterns: HTTP evaluator, verification (test-suite), simulation
(multi-scenario), and composite (multi-signal). Each includes artifact,
evaluator code, CLI command, sample output, and usage guidance.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Entire-Checkpoint: fd73459de3f2

Author: ASRagab