roles: fixer + weaver — port from references/endo-but-for-bots/

Copied from kriscendobot/garden skills/yarn-lock-separate-commit/SKILL.md
(only that file) at commit 74eee479382f70fe54f668b92c531b834c85b5a5:
https://github.com/kriscendobot/garden/blob/74eee479382f70fe54f668b92c531b834c85b5a5/skills/yarn-lock-separate-commit/SKILL.md

yarn-lock-separate-commit/SKILL.md

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+---
+created: 2026-05-13
+updated: 2026-05-13
+author: liaison
+---
+
+# Skill: yarn-lock-separate-commit
+
+Adopted from `references/endo-but-for-bots/skills/yarn-lock-separate-commit.md`.
+
+Every change that touches `yarn.lock` ships in its own commit, separate from the `package.json` change that caused the update, with the message `chore: Update yarn.lock`.
+
+## Why
+
+A separate lockfile commit can be dropped and regenerated cleanly on rebase. A combined commit turns lockfile churn into merge conflicts that have to be resolved by re-running `yarn install` and hand-stitching, which is error-prone and pollutes history.
+
+## Procedure
+
+After making the dep change in `package.json`:
+
+```sh
+git add packages/foo/package.json
+git commit -m "feat(foo): add bar dependency (#NNNN)"
+
+npx corepack yarn install
+git add yarn.lock
+git commit -m "chore: Update yarn.lock"
+```
+
+When force-pushing a rebased branch, the order of the two commits matters: put the lockfile commit *after* the package.json commit, so a reviewer dropping the lockfile commit lands at a still-coherent state.
+
+## Pitfalls
+
+- **`git commit --amend` on the package.json commit silently drags the lockfile in if staged.** Stage and commit the lockfile last.
+- **Accidental combining.** If caught on review, `git reset HEAD~1`, re-stage selectively, and recommit as two.
+- **Package renames invalidate the lockfile.** Renaming a workspace's directory or `package.json:name` changes the workspace key (`"@scope/<name>@workspace:packages/<dir>"`) inside `yarn.lock`. Still ships in its own `chore: Update yarn.lock` commit, regenerated by re-running `npx corepack yarn install` after all renames are in place. Don't hand-edit the workspace key; the install produces the canonical form.
+
+## Notes from the field
+
+- _2026-05-13_: adopted from the reference. Session example from PR 71 lives in the journal, not here.