feat: add exact show state command to openwebui examples

[rlippmann]

What changed

• added exact-match local show state command to both OpenWebUI example pipes
• command behavior is deterministic and local-only:
  • exact match on user_input.strip().lower() == "show state"
  • no downstream LLM call
  • no preprocessor call on this path
• response is a concise state summary with:
  • premise
  • use policies
  • prohibit policies
  • pending clarification status
• ensured show state remains trace-free even when trace valve is enabled
• added/updated OpenWebUI tests for:
  • local summary behavior
  • no downstream call
  • pending yes/no coverage
  • preprocessor bypass behavior for show state
  • non-exact variant normal routing
• updated OpenWebUI README with concise show state note and replaced competitive "win" wording with neutral "why this matters"

Why

• provide a simple, explicit way to inspect current compiler state in OpenWebUI without relying on trace output
• keep command handling strict and deterministic while preserving existing passthrough/update/clarify behavior
• improve user-facing documentation tone and clarity

Checklist

• pre-commit run (uv run pre-commit run --all-files)
• tests pass (uv run pytest)