feat(cli): add environment trajectory commands

[salim4n]

Summary

• add defineEnvironmentEpisode() for reusable, CLI-loadable environment episode modules
• add ignition-agent-trainer environment run <episode.ts> with seed, max steps, policy id, trajectory id, metadata JSON, JSON/Markdown trajectory reports, and offline record count output
• make examples/rag-environment-episode export a default episode definition while preserving its direct dev command
• update CLI, environment, RL, example, root README, audit, readiness, and backlog docs

Validation

• bun install
• bun run lint
• bun run typecheck
• bun test packages/environment/src/environment.test.ts packages/cli/src/index.test.ts
• bun run --filter './examples/rag-environment-episode' dev
• bun run --filter '@ignitionai/agent-trainer-cli' dev -- environment run ./examples/rag-environment-episode/src/index.ts --seed 7 --max-steps 10 --policy-id scripted-rag-policy --trajectory-id rag-cli-smoke --json /tmp/iat-cli-environment-smoke/trajectory.json --markdown /tmp/iat-cli-environment-smoke/trajectory.md --offline-records
• bun run test
• bun run build
• bun run pack:check
• git diff --check