Reuse verified Windows cleanup parents for present Included Files trees

[Infiland]

Problem

The focused #826 diagnosis found that its exact 10,000-entry timeout is dominated by probing descendants below an already-proven-absent moved stage directory. Skipping those descendants fixes that concrete job blocker.

A separate scaling cost remains for genuinely present recorded trees on the Windows verified-path fallback. Each file independently captures and re-verifies the same parent/ancestor chain during source and tombstone state checks.

Measured modeled-Windows work for a flat present 1,000-file tree:

• 5,014 fallback ancestor captures
• 11,016 ancestor re-verifications
• 164,232 lstat calls

The current shape projects to roughly 1.64 million lstat calls at 10,000 present files. This is not the moved-stage state exercised by #826, so solving it there would turn a one-line fail-closed optimization into a much larger Win32 transaction rewrite.

Related: #768, #770, #771, #826

Scope

• Group present-tree cleanup by verified parent or retain a bounded parent binding so invariant ancestor work is not repeated for every flat child.
• Preserve no-follow, exact identity/digest, junction/reparse, hard-link, mount, rollback, tombstone, and late-replacement defenses.
• Keep Windows fallback behavior explicit; do not assume POSIX dir_fd support.
• Add deterministic operation-count coverage for genuinely present flat and nested trees.

Acceptance criteria

• Present flat-tree cleanup performs work linear in entries plus directory depth, not entries times repeated ancestor depth.
• Operation-count tests fail on the current repeated-capture shape and remain stable across at least two substantially different entry counts.
• Late parent relocation/replacement, junction/reparse, mount, digest, hard-link, and read-only adversarial tests preserve unknown content.
• The exact native Windows transaction job, Pyright, Ruff, the full unit suite, and Godot 4.7.1 validation pass.