W06.A.5 — mv-across-dirs LD_PRELOAD + planner Rename/Create suppression

[espadonne]

Summary

• LD_PRELOAD the shim when invoking mv in mv-across-dirs-undo-fbsd.sh. With W06.A.3 (PR W06.A.3: wire LD_PRELOAD shim notifications into journal events #47) wiring landed, the shim's rename(2) interposer now fires for cross-watch moves and the daemon journals them as TreeOp::Rename.
• Smoke gating tightened: all three cases (intra-watch, unwatched dst, unwatched src) must PASS — no more "documenting gaps" tail.
• Planner fix: when the shim emits a TreeOp::Rename(to=P) AND the kqueue dir-diff also observes a TreeOp::Create(P) for the same mv (two views of one logical action), suppress the Create's Unlink inverse. The Rename's inverse (Rename(to → from)) is authoritative; the duplicate Unlink was deleting the just-restored file.

Results

On shit-fbsd (FreeBSD 14.4):

Case	Before W06.A.5	After
case1 — intra-watch mv	FAIL (file not restored)	PASS (full undo)
case2 — mv to unwatched dst	PARTIAL (dst leftover)	PASS (full undo)
case3 — mv from unwatched src	DATA LOSS	PASS (full undo)

Full 11-smoke regression sweep green: rm, mkdir, chmod, touch-edit, pkg-install, service-restart, vim-edit, git-commit, cp-recursive, sed-inline, make-install.

Closes the W08 cross-watch-rename gap that motivated unifying W06 + W08.

Test plan

• cargo test -p shit-planner --lib — 431 + 1 new test (rename_plus_duplicate_create_suppresses_unlink_inverse)
• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo build --workspace --release
• mv-across-dirs-undo-fbsd.sh on shit-fbsd — case1/2/3 all PASS (full undo)
• Full BSD smoke regression — 11/11 green
• freebsd-smoke CI green on PR (watching)