fix: close the gaps the review of the trial-5 fixes found

- park-attempt-files: parks in the git dir (outside the work tree, so Sub-step C.2 never registers a parked file again), reads a path with a space, names a new file under a header it cannot read, parks a symlink, never overwrites a parked file, and exits 1 while a file the attempt made is still in the tree; the upward diff is saved in one form whatever the git config.

- brief-validator: BRIEF_SC_NOT_RUNNABLE only when a later backticked span is a command; a criterion that only names a flag or a path stays prose (Handover 1 says so now).

- review ids: counted over the final list (runContract), as fill-finding-ids counts review.md; trimmed_count matches rows by id; engine-findings and fidelity-diff use computeFindingIds; the --workflow dedup keeps one source's different findings apart, the decision-23 put-back stays one copy per triplet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

commands/trekbrief.md

@@ -820,7 +820,8 @@ If the validator returns errors, report them to the user and offer to
 re-enter Phase 4 with the validator's hints in scope. If only warnings,
 note them in the final report — except `BRIEF_SC_NOT_RUNNABLE`: a success
 criterion whose command `/trekreview` will never run (the product's own
-binary, `jq`, `grep`, a pipe). Name each one to the user in plain words and
+binary, `jq`, `grep`, a pipe, or a command that stands after a flag or path
+in backticks). Name each one to the user in plain words and
 offer to rewrite it as a script under `tests/` that the criterion runs
 (`bash tests/<script>.sh` exits 0) before the brief is approved; if the user
 keeps it, it stays a criterion a human judges, and the report says so. The