fix(lefthook): remove duplicate git-lfs pre-push command

Lefthook v2 runs `git lfs pre-push` internally for pre-push hooks (per
docs/usage/features/git-lfs.md; confirmed in internal/run/controller/
lfs.go where the internal handler invokes `git lfs pre-push <remote>
<url>` with a buffered `cachedStdin`). Our manual `git-lfs:` command
in lefthook.yml was a second invocation against the same remote; the
duplicate is directly visible in `LEFTHOOK_VERBOSE=1` output as
`[git-lfs] executing hook` (internal) followed by `[lefthook] run:
git lfs pre-push` (manual).

The previous fix attempt (piped: true, commit 1b06804) was based on a
wrong understanding of `piped`'s semantics — `piped` controls
fail-fast behavior, not stdin routing or sequencing. Default lefthook
behavior is already sequential per docs/configuration/parallel.md.
That "fix" was placebo; incident 2 (F2 push, zero LFS objects, commit
99eedb6) proved it.

Phase A investigation: documentary + source confirmation that lefthook
owns the LFS pre-push call. Phase B sandbox test against a filesystem
remote confirmed the duplicate execution in logs but did NOT reproduce
the production hang — likely because the duplicate manual call against
a local remote has no LFS server to interact with. A network-y remote
(Gitea over SSH/HTTPS) appears to be part of the trigger. Two
mechanisms remain plausible (H1: PTY-stdin without EOF in
`while read` loop per docs/configuration/use_stdin.md; H4: server-side
LFS interaction on the duplicate call). Both are eliminated by the
same fix: remove the manual command. LFS uploads continue to work via
lefthook's internal handler (verified in sandbox post-fix).

Regression coverage: scripts/test-lefthook-pre-push.sh asserts exactly
one internal LFS invocation, zero manual ones, and `Uploading LFS
objects: 100%` present, against a disposable sandbox.

See dev-docs/ADR-LEFTHOOK-LFS-INTEGRATION.md for full context, both
misconceptions to prevent regression, and the alternative-scenarios
playbook if Phase E ever regresses.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

scripts/README.md

@@ -38,3 +38,16 @@ bash scripts/sync-claude-docs.sh help
 Upload everything in `.claude-sync/` (including `SYNC_MANIFEST.md`) to the
 Crewli Claude Project Knowledge, replacing existing versions. The manifest is
 what Claude Chat uses for drift detection against the current HEAD.
+
+## Lefthook + Git-LFS pre-push smoke test
+
+```bash
+bash scripts/test-lefthook-pre-push.sh
+```
+
+Builds a disposable sandbox, mirrors the repo's `lefthook.yml` + `.githooks/`,
+and runs a push to verify (a) push completes, (b) exactly one internal LFS
+invocation, (c) zero manual `git lfs pre-push` commands, (d) LFS upload
+happens. Run this after touching `lefthook.yml` or the LFS configuration.
+Background and what each failure mode signals:
+`dev-docs/ADR-LEFTHOOK-LFS-INTEGRATION.md`.