Windows: validate directory rejection with simulated reparse metadata without link fixtures #2924

The Windows verify_directory_reason_rejects_reparse_component test creates real symbolic links and junctions. On the current development host, symbolic-link creation fails with Windows error 1314, blocking validation of #2892 despite the unchanged production behavior.

The user requested an alternative without links for this specific correction, approved preparation and coverage review, and explicitly authorized a Git worktree for this workaround while P01 remains suspended. Other pre-existing link tests remain unchanged; their future correction is tracked separately in #2922.

Scope: src-tauri/src/path_identity.rs and .github/workflows/pr-regression-gates.yml. Use the architect-reviewed private shared verification algorithm with simulated Windows reparse metadata, preserve exact typed errors and ordinary-directory controls, and explicitly reconcile the obsolete AC_REQUIRE_WINDOWS_LINK_TESTS producer/consumer. Public production behavior must remain unchanged.

Coverage limitation: simulation does not verify real Windows symbolic-link/junction metadata or the corresponding filesystem integration. Declare this loss explicitly; no claim of equivalent integration coverage, skipped tests, privilege changes or CI waiver.

Candidate: .ac/plans/2432-identity-layers/plan-v4-windows-no-links-test.md, SHA256 4a1f40ceb7d6e4849146cf74165283a132b1a5c160efede78f527ea7ccdebb7b. Rust and Grinch approved its design; the delivery sequence is being updated for the authorized worktree exception. Implementation must follow the final frozen, approved plan and normal verification gates.

Deliver independently, then integrate the landed correction into the preserved P01 branch. Do not close #2432 or #2892 with the corrective PR. No distribution build requested.