fix(ci): drop uv cache + clarify entry skill action/conversation split

[dean-harel]

Summary

• CI: Remove `enable-cache: true` from the `astral-sh/setup-uv` step in `entry-publish.yml`. The cache step required a `uv.lock` that doesn't exist (scripts use PEP 723 inline metadata, not a project lockfile), and bombed with `No matches found for glob **/uv.lock` before any publish work ran. Surfaced on PR entry: don't conversate, navigate #12, the first end-to-end run of the publish pipeline introduced in PR feat: X Articles syndication pipeline #10.
• Entry skill: Clarify that artifacts are only written when the user picks a listed action — free-form follow-ups are conversation, not revise instructions. Add a research.yaml rule that later sections should build on earlier ones.

Test plan

• Once merged, re-trigger PR entry: don't conversate, navigate #12 by removing and re-adding the `ready` label and confirm the Publish Entry job gets past `setup-uv`

[github-actions]

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