Phase 1: add RL-Kernel fast/consistency mode parsing

[inaniloquentee]

Part of #6, based on vime/RL-Kernel-vime-integration-roadmap.md Phase 1: Contract and Telemetry Layer.

Goal

Add the public vime controls for RL-Kernel fast-path selection and rollout-training consistency auditing without changing native behavior by default.

Scope

• Add --rlk-fast {off,auto,strict}.
• Add --rlk-consistency {off,audit,strict}.
• Add environment aliases VIME_RLK_FAST and VIME_RLK_CONSISTENCY with the same allowed values.
• Preserve compatibility with current RL-Kernel flags:
  • --enable-rl-kernel implies --rlk-fast auto unless explicitly overridden.
  • --rl-kernel-strict maps to --rlk-fast strict for enabled operators.
  • --rl-kernel-ops remains the operator allowlist.
• Centralize the resolved values in one config object used by mode selection and audit code.

Acceptance Criteria

• Native vime behavior is unchanged when both switches resolve to off.
• CLI values, env values, and explicit override precedence are covered by tests.
• Invalid values fail early with an actionable error.
• --rlk-consistency audit is accepted even when acceleration is disabled.
• Help text clearly describes the two switches as orthogonal controls.