Refactor Monty REPL entrypoint helpers

[rita-aga]

Summary

• split monty_repl/src/lib.rs helpers into focused modules for output buffering, run control, REPL state, REPL driving, telemetry, tool results, and the WASM random backend
• add an architecture ratchet so monty_repl/src/lib.rs stays below the repo-health giant-module threshold
• preserve behavior; dispatch.rs only received rustfmt reflow

Verification

• cargo fmt --check --manifest-path os-apps/paw-agent/wasm/monty_repl/Cargo.toml
• git diff --check
• cargo test --manifest-path os-apps/paw-agent/wasm/monty_repl/Cargo.toml (44 passed)
• cargo test -p temperpaw --test session_turn_architecture (14 passed)
• cargo check --manifest-path os-apps/paw-agent/wasm/monty_repl/Cargo.toml --target wasm32-wasip1

Proof

• monty_repl/src/lib.rs is now 840 lines, down from 1581, and has a test-backed budget of < 900 lines.
• This is the first concrete cleanup follow-up from Patrol's repo-health finding class for giant WASM modules; dispatch.rs and entity_ops.rs remain future cleanup candidates.