gate: irrecoverable allows git -C${R} reset --hard (braced var glued to a git global); chmod rule over-blocks a 777 path #405

Found by the 2026-10-03 deep-audit of fea6ebd..2c3fffa (Codex checker, both reproduced independently at 2c3fffa with bash hooks/gates/irrecoverable.sh).

F1 (P1, bypass). A braced variable glued to a git global option is allowed, so destructive git commands pass. Exit 0 (should be 2): git -C${R} reset --hard, git -C${R} push --force origin main, git -C${R:-.} reset --hard. The unbraced forms are denied (git -C$R reset --hard, git -C"$R" ..., git --git-dir=${R} reset --hard all exit 2). The #383 _Glued fix (GH #375) did not cover this shape: hooks/gates/irrecoverable.py:1663-1688 (_git_words) joins glued runs, and :1984-1991 appends the re-read window only when it returns one. Find why the {...} part is not joined (likely {/} handling in _split_ops or _tokens), fix it in the same second-reading style (deny in either reading wins), and check the sibling walks from #382 are not affected twice. Needs its own differential (fixtures, transcript replay, fuzz) per docs/reference/repo-gotchas.md.

F2 (P3, over-block, fails closed). The chmod rule searches every argument for 777 or a+rwx (hooks/gates/irrecoverable.py:1717), so chmod -R 755 777 and chmod -R 755 a+rwx exit 2 although the mode is 755. Identify the mode argument (first non-option word, after --/-R etc.) and test only that; keep chmod -R 777 x denied.