docs(skills): tag Actor development CLI calls with --user-agent

[patrikbraborec]

Adds the --user-agent telemetry attribution flag to the Actor-development skills, following the apify-agent-skills/<skill> convention already used in apify-ultimate-scraper.

What changed

File	Tag	Changes
skills/apify-actor-development/SKILL.md	apify-agent-skills/apify-actor-development	New Telemetry attribution (required) section after Prerequisites; flag on the three apify create -t … template commands, quick-start steps 7/8 (run/push), the whole command reference block (header note + inline), and the remote Actor call flow
skills/apify-actorization/SKILL.md	apify-agent-skills/apify-actorization	Same section; flag on the quick start, the 9-step checklist, apify init, both apify run forms, apify push, and the pre-deployment checklist
commands/create-actor.md	apify-agent-skills/apify-actor-development	New "Tag every CLI call" core principle; flag on Phase 8 apify run and Phase 9 apify push
skills/apify-generate-output-schema/SKILL.md	apify-agent-skills/apify-generate-output-schema	Flag on its single apify run mention

Notes

• --user-agent is a global flag accepted by every apify command, even though it is hidden from --help. Verified against apify-cli 1.10.1: apify validate-schema --user-agent … runs normally, while an unknown flag errors with Unknown flag provided.
• The comment column in the apify-actor-development command block was re-aligned, so a few untagged lines (login, logout, secrets, api, help) show up in the diff as whitespace-only changes.
• Auth commands and reference-file prose mentions of apify run were left untagged; the block-level note covers them.
• commands/create-actor.md reuses the apify-actor-development tag so command-driven and skill-driven runs land in the same telemetry bucket - easy to split into apify-agent-skills/create-actor if you'd prefer them separate.