Load .env in apify run #1569

apify run reads local values only from environmentVariables in actor.json. .env is the format the rest of the industry uses, and it becomes the recommended place for local env vars.

Scope

• Read .env from the Actor directory (next to .actor/) when it exists, and add its values to the run environment (src/commands/run.ts).
• Parse it with Node's built-in util.parseEnv. The CLI requires Node.js 22, so no new dependency is needed.
• Apply this precedence, lowest to highest: shell environment, variables the CLI sets for the run, environmentVariables from actor.json, .env. Only the last step is new.
• Treat values as literal. @secret references aren't resolved in .env.

Out of scope

• The deprecation warning for environmentVariables. It has its own issue.

Done when

• Tests cover the precedence order and a run without .env.

Depends on

• .env is never uploaded (Never upload .env, and ignore it in Git by default #1568)