#27 merge contract truth: CI gate in scratch worktree, never-touch-main, orchestrator integrates; docs lied

SOURCE: swarm friction #6 (verified). Behavior is CORRECT and stays: f0rge merge = CI gate in a scratch worktree, applies patch, runs all steps, verdict pass|fail, NEVER touches main or git branches; orchestrator ffs the applied sha + deletes branch + closes the PR. No auto-integrate (bitter lesson; #20 non-goals). The DOCS lied: contract line "merge: applies prints conflicts never resolves; PR stays (state: merged), branch deleted" implies f0rge integrates and deletes. FIX: contract merge line becomes a true teaching line: "merge: CI-gates patch in scratch worktree; never touches main or branches; prints conflicts, never resolves; you integrate (ff) + delete branch"; same truth in merge -h and spec [merge-record, procedure]. DONE: contract/merge-h/spec all true; golden + budget tests pass.