feat(分支基準): 參考與來源分支一律取遠端 origin，動作前先 fetch

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

skills/maintain/SKILL.md

@@ -17,7 +17,7 @@ All wiki reads and writes go through `jsc-gitea:wiki`.
    4. Exit 0 means the stage is locked. Run this gate only when the stage changes; inside the maintenance stage the lock already covers every project, so never re-gate between projects.
 2. Read `MAINTAIN_CONTENTS` via `jsc-gitea:wiki` and filter projects **still inside their maintenance window**: start date ≤ today, and (end date is NULL or ≥ today).
 3. Every project **MUST run as a sub agent** with this flow:
-   1. Switch the project to the `develop` branch, falling back to `master`, and pull to latest.
+   1. Run `git fetch --prune origin`, then switch the project to `develop`, falling back to `master`, and bring it up to `origin/{該分支}` — the remote is the basis, never the local branch. Local and remote diverged → report and skip that project; never `pull --rebase`, `reset` or discard anything on your own.
    2. Propose **at least five** maintenance methods and apply the ones that fit the project, for example:
       - dependency updates (reuse `jsc-pkg:pkg-update`)
       - security vulnerability scan and patching