fix(wine): release drop target after drop or leave

[silaswester]

Summary

• independently backports Wine upstream commit 8ca473d0c6aa3b2d2711de4b6d24fe2c85fa6c48 to release the retained IDropTarget at the end of drag_drop_drop and drag_drop_leave.
• updates the frozen patch-series manifest, required-tail policy, and CHANGELOG.
• adds a deterministic source-context applicability test that proves the backport applies to the pinned Wine 11.13 source archive without offset, fuzz, or context drift.

Issue

• Targets upstream issue shibco/ableton-linux#116 (drag & drop stops working at random intervals).
• This PR is a third, independent implementation in silaswester/ableton-linux. It does not update, supersede, or rebase the two earlier open PRs (#1 from task-t_bf605a9-116 and fix/user32-drop-target-lifetime) so all three implementations remain available for side-by-side comparison.
• The upstream repository and issue stay read-only.

Source-equivalence / provenance

• Source patch is byte-for-byte identical to upstream commit 8ca473d0c6aa3b2d2711de4b6d24fe2c85fa6c48:
  • Author: Zhou Zhang <zhangzhou@uniontech.com> (mail header preserved)
  • Author date: Fri, 17 Jul 2026 15:22:15 +0800 (mail header preserved)
  • Subject: [PATCH] user32: Release drop target at the end of drag_drop_drop and drag_drop_leave. (preserved verbatim, including the wrapped continuation)
• Local dlls/user32/clipboard.c base SHA256 (extracted from vendored vendor/wine-base-5c23dd1c.tar.zst) equals wine-mirror/wine's file at the upstream parent commit c5cb1e78.
• Local dlls/user32/clipboard.c SHA256 after applying patches/0099-user32-Release-drop-target-at-the-end-of-drag_drop_d.patch equals wine-mirror/wine's file at upstream 8ca473d0.

Acceptance matrix

Criterion	Result	Evidence
Patch preserves upstream author / date / subject	PASS	scripts/test-user32-drop-target-lifetime.sh (preserves upstream mail authorship and subject)
Patch covers drag_drop_leave retained-target cleanup	PASS	scripts/test-user32-drop-target-lifetime.sh (covers drag_drop_leave retained-target cleanup)
Patch covers delayed drag_drop_drop release	PASS	scripts/test-user32-drop-target-lifetime.sh (covers delayed drop-path release after drop processing)
Patch applies cleanly to pinned Wine 11.13 source context	PASS	scripts/test-user32-drop-target-lifetime.sh (applies cleanly to pinned Wine user32 source context)
Required Wine series tail is 0099-... patch	PASS	./scripts/build-audit.sh --check-series-policy patches/SERIES.sha256 (OK: required Wine and PipeASIO series tails are present.)
Frozen patches/SERIES.sha256 re-verifies	PASS	sha256sum -c patches/SERIES.sha256 (all 106 entries OK)
Pointer-safety invariants preserved	PASS	make check (pointer safety checks: PASS)
Vendor archive integrity	PASS	make verify (OK for every vendored archive)
Required-tail policy still passes after backport	PASS	scripts/test-release-policy.sh (patch series cannot lose either required terminal member)

Pre-existing failure isolated to unchanged baseline: make test reaches scripts/test-desktop-integration.sh, which fails with installer kit is missing its PipeWire compatibility check both on this branch and on clean main. The failure is unrelated to this change.

Documentation reconciliation

• BUILDING.md documents that make test now exercises the patch 0099 applicability invariant and that the deterministic source checks preserve the link to upstream commit 8ca473d0c6aa3b2d2711de4b6d24fe2c85fa6c48.
• CHANGELOG.md records the new backport, the upstream commit linkage, the runtime reproduction caveat (no Live runtime reproduction captured), and the relation to issue 116.
• patches/BASE.txt reconciles the series count, the 0099 provenance entry, and notes that runtime behavior is not proved by the deterministic checks.

Scope evidence

• git diff --name-status origin/main...HEAD: 0 deletions, 8 scoped files
• Files: BUILDING.md, CHANGELOG.md, Makefile, patches/0099-user32-Release-drop-target-at-the-end-of-drag_drop_d.patch (added), patches/BASE.txt, patches/SERIES.sha256, scripts/build-audit.sh, scripts/test-user32-drop-target-lifetime.sh (added).
• Branch base: exact origin/main at 4004f205b67546d559e342f4ab62fd78b03fed5b. Local head SHA: 0184ab996d3b856d300f83c39d6be458c78d2eed.
• No deletion, no rename, no copy from elsewhere, no edit outside the eight listed files.

Known defects / limits

• Deterministic source tests prove exact upstream source equivalence and clean applicability to the pinned Wine 11.13 source archive. They do not prove that drag-and-drop behavior changes in a running Live. A controlled Live A/B on at least one affected host is the appropriate next gate before treating issue 116 as resolved.
• make test desktop-integration failure predates this branch and is unrelated to the patch 0099 change.

Boundaries

• target repo: silaswester/ableton-linux only
• base branch: main
• upstream repository: read-only; no issue, label, comment, or branch touched
• branch task-t_47cee33-116 is left for Matt's comparison review; do not merge automatically
• leaves draft open in this repo only; the previously-published open PRs #1 and #2 are not modified