Pr base is develop

PRs must target develop, not main. Feature branches stay in sync with develop by merging develop into the branch (never rebasing).

Why: develop is the integration branch that stays ahead of main. Targeting main drags in dozens of unrelated commits from the develop..main gap, making the PR diff unreadable and triggering unnecessary CI. 2026-08-10 user explicitly asked: 解决冲突优先使用 merge（已写入 github-workflow 技能的"冲突解决"一节）。PR 采用 squash 合并，因此特性分支内 merge develop 产生的合并提交会被 squash 掉，不会污染 develop 历史。

How to apply: When creating a PR, always use --base develop. When the PR branch falls behind develop or hits a merge conflict, resolve it with git merge origin/develop (resolve conflicts manually, keep both branches' logic blocks) — do NOT rebase. Merge commit only contains the conflict resolution; test fixes go in separate commits.

Squash 后开新 PR 的坑（2026-09-01 #901）：develop 用 squash 合并（旧提交不在 develop 历史里）。若在已合并的本地旧分支上继续提交并推新 PR，merge-base 停在 squash 之前，GitHub 会把已合并的文件又列进新 PR 的 files（用户看到"改的文件不对"）。解法：git fetch origin develop && git rebase --onto origin/develop <已合并分支旧HEAD> 把新提交单独变基到最新 develop 再 force push（--force-with-lease）。此场景与"冲突解决用 merge"不冲突：冲突仍用 merge，squash 历史分叉用 rebase --onto 整理。