docs(skills): correct APIFY_TOKEN CLI authentication guidance

[marekh19]

Relates to apify/apify-plugins-internal#21

The skills told agents the Apify CLI reads APIFY_TOKEN from the environment. It doesn't — getToken() reads the OS keyring or ~/.apify/auth.json and never touches process.env. Agents following this exported the variable, got "not logged in", and had no next step.

All four files now point to apify login --token TOKEN for headless auth, and explain that APIFY_TOKEN is read by the Apify SDK inside a running Actor rather than by the CLI.

In apify-actor-development and apify-actorization the security note said to "prefer environment variables" over apify login -t. Fixing only the wrong sentence would have left that note steering agents away from the one method that works headlessly, so the warning is kept but redirected: pass the token from a variable or secret store rather than typing it inline.

skills/apify-sdk-integration/SKILL.md is untouched — its APIFY_TOKEN references are about the SDK and are correct.

[jirispilka]

I think this is mostly for builders. I added them to the review and removed AI

[marekh19]

I just found out that apify/apify-cli#1246 and apify/apify-cli#1293 exist. Putting this on hold for now.

[l2ysho]

Relates to apify/apify-plugins-internal#21

The skills told agents the Apify CLI reads APIFY_TOKEN from the environment. It doesn't

Well it does, even if it is not super obvious, but at least run command use it (correctly marked by @marekh19 ). I tried to fix the precedence problem in PR #1293 but I keep breaking some other parts of the flow :/ There are some known problems in auth and token flow, we already discussed this with @vladfrangu and there is a plan for bigger refactoring in next weeks (months). I will link this issue to the epic so we do not forget about it.