docs: the back-merge takes whichever shape dev earned

[lchoquel]

The /release skill's Particulars claimed the back-merge is always a merge commit and never a fast-forward. That was true only while release branches were squashed into main. Under the merge-commit policy main is a descendant of dev-at-the-cut, so /ledger-land's merge of origin/main into dev fast-forwards whenever nothing landed on dev after the cut, and makes a merge commit only when something did.

The bullet at .claude/skills/release/SKILL.md:74 now names both shapes and keeps the changelog as the one conflict to expect, matching the workspace instruction in CLAUDE.md and the wording pipelex-sdk-js's release skill already carries.

The rest of the skill was swept for the same assumption: the only other merge sentence is line 21, which holds under either shape. No changelog entry — a skill-only docs change gets none here, per #85.

One /rev pass at profile 1 (cubic), round 1, recorded on the item: no findings.

Closes L-260908-78bb9c

🤖 Generated with Claude Code

https://claude.ai/code/session_01JjRK9NyFp4vsif7LAFQmYz

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Summary by cubic

Fixes the /release skill's back-merge description so it matches the actual behavior under the merge-commit policy: the bullet previously claimed the back-merge is always a merge commit, but it's now a fast-forward when nothing landed on dev after the cut, and a merge commit only when something did. The corrected bullet names both shapes and keeps the changelog as the one conflict to expect. A sweep of the skill found no other places with the same assumption. Closes L-260908-78bb9c.

^{Written for commit 4f05904. Summary will update on new commits.}

[lchoquel]

/rev profile 1 (quick), round 1 — reviewer: cubic (1.10.5, authenticated). Target: this branch against origin/dev, 2 changed lines in 1 file.

No findings. Nothing fixed, nothing deferred. Recorded on the ledger item.