q99: drop the 218-byte embedded-newline path from the index (blob 7639369 stays in history)

Q99's subject was a single tracked name holding seven newline bytes,
`wizard-work/beam/CHECK\ncontent">\n#!/bin/bash\n...`, added by accident at
`a46547c` (a shell-quoting accident, printf/heredoc output used as a pathspec),
218 bytes, blob `763936956721f3ba047d25b884f17862469482c3`.

Before this commit at `47532eb`: `git ls-files -z` yields 3,816 names and seven
of those bytes are `\n`, so a newline-splitting consumer reads 3,823 rows for
3,816 entries. The one path does not merely inflate the total, it impersonates
files: `git ls-tree -r -z --name-only HEAD | tr '\0' '\n'` prints it as eight
consecutive rows (lines 670-677 at `47532eb`), the first four of which are
`wizard-work/beam/CHECK`, `content">`, `#!/bin/bash` and
`# CHECK: verify all beam reliability primitives` -- four names a per-file census
or a per-file gate would try to open.

Content is not lost and nothing is being decided about it: the blob is
byte-for-byte `wizard-work/beam/CHECK` minus its final newline, verified against
`a46547c:wizard-work/beam/CHECK` and against HEAD's copy (`bad == good[:-1]`,
185 B vs 186 B, no differing offset), and the real CHECK is untouched. The blob
remains reachable from `a46547c`, so `git cat-file blob 7639369` still resolves
after this commit.

Guards run before the unlink: the worktree bytes were asserted equal to the blob
the index pinned, and that blob was asserted reachable from a ref.

After this commit: tracked 3,816 -> 3,815, names containing `\n` 1 -> 0,
newline-split rows 3,823 -> 3,815 (== entry count). An index-derived census keyed
on backslash-escaped names (`q99_census.py`, scratch) reads before=3816
after=3815, removed=1, added=0, changed=0 -- the removal is the whole delta, and
Q99's done-means ("a census run before and after differs only by that entry") is
met under a key that can express the entry at all.

Gate A/B on a scratch clone, committed there so HEAD moved: `tools/verify.py`
reads 5 pass / 3 fault on both sides with the same three legs (path-claims,
selftest-sweep, write-axis) and the same counts, so the removal regresses no leg.
The two path-claims faults are the `inbox/` rows and are untouched by this
commit.

Probes (read-only, outside the repo, under the volt profile cache):
/root/.hermes/profiles/volt/cache/scratch/q99/
  newpath_probe.py, pin_content.py, q99_census.py, q99_worktree_state.py,
  q99_apply_live.py, census_before.tsv, census_after.tsv, verify_after.txt

wizard-work/beam/CHECK content"> #!/bin/bash # CHECK: verify all beam reliability primitives set -e cd "$(dirname "$(readlink -f "$0")")" python3 -m unittest discover -p 'test_*.py' -v python3 toposort/test_toposort.py

@@ -1,6 +0,0 @@
-#!/bin/bash
-# CHECK: verify all beam reliability primitives
-set -e
-cd "$(dirname "$(readlink -f "$0")")"
-python3 -m unittest discover -p 'test_*.py' -v
-python3 toposort/test_toposort.py