Add the apify env namespace and apify env ls #1570

No command shows the env vars of an Actor version on the platform. This issue adds the apify env namespace, the targeting rules that every apify env command shares, and the first command.

Scope

• Add the env namespace (src/commands/env/_index.ts), register it in src/commands/_register.ts, and add it to the docs categories in scripts/generate-cli-docs.ts.
• Add a targeting helper that all apify env commands use:
  • Actor: read it from .actor/actor.json in the current directory. --dir <path> picks an Actor folder in a monorepo. --actor <ID or username/name> targets an Actor without a local project.
  • Version: use --version, then version from actor.json, then 0.0. This is the order apify push uses.
• Make apify env ls print a table with the name, the type (secret or plain), and the value of plain variables. Never print a secret value.
• Support --json.

Done when

• The command works for CLI-pushed and Git-sourced Actors.
• It fails with a clear message when the Actor or the version doesn't exist.