fix(graceful-handoff): two defects found by the first real smoke test (v3.2.1)

The pipeline had never been run against an actual repository — every test in
the suite is either a prose-grep over SKILL.md or a unit test that asserts key
presence. Running it against scratch repos (private remote, and public `open/`
remote with and without a gitignored STATE.md) found two defects living under
a 42/42-green suite.

1. dirty_files truncated the first path. gitOk() trims every command's output,
   but `git status --porcelain` puts the worktree status in column 2, so a
   modified-but-unstaged file is " M path". The trim ate the leading space and
   the fixed slice(3) then ate the first character: app.js was reported as
   pp.js. Only the first line is affected, which is why it survived — no test
   asserted dirty_files VALUES, only that the key existed. Porcelain now goes
   through a non-trimming gitOkRaw().

2. The commit message claimed a STATE.md update it did not contain. The
   message was hardcoded to "oppdater STATE.md" regardless of what was staged.
   On every `open/` repo STATE.md is gitignored, so the handoff commit carries
   only the --also paths. Git history is the regime's long-term log; it was
   systematically wrong about its own contents.

Also promotes the leak condition from advisory to hard gate. A public remote
whose STATE.md is not yet gitignored is the state a FRESH open/ repo starts
in, and should_commit_state was true there — the ritual only mentioned
leak_warning, then committed. It now lands in errors[] (step 2 stops on a
non-empty errors[]), should_commit_state is false, and --commit refuses to
stage STATE.md. Explicit --also paths are still honoured: the gate protects
STATE.md, not the commit as a whole.

And corrects SKILL.md's justification for the single-line rule. It claimed a
wrapped rationale= replaces the board's next step with garbage; board.sh in
repo-mailbox 0.20.3 tracks a comment to its closer, so that no longer follows.
The rule stands, restated with the risk that is still real: a rationale
containing the closer sequence ends its own comment early.

Tests 42 -> 48, all six written failing first.

Still unverified: that /graceful-handoff loads as a user command (#26251), and
that a cross-plugin Skill invocation of repo-mailbox:route passes from a
sub-scoped skill. Both need the catalog ref bumped so the version is installed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RvLY4FwbzY157oVqwnkHD8

tests/skill-structure.test.mjs

@@ -94,6 +94,23 @@ test('SKILL.md warns that the three comment lines must stay single-line (board.s
   assert.match(s, /ÉN linje/);
 });
 
+test('the single-line rule no longer rests on a consequence board.sh has since fixed', () => {
+  // repo-mailbox 0.20.3's board.sh tracks an HTML comment to its closer, so a
+  // wrapped rationale no longer leaks comment internals into the board excerpt.
+  // The rule stands; the stated consequence had to stop being the reason.
+  const s = skill();
+  assert.doesNotMatch(s, /erstatter derfor neste steg på tavlen med søppel/);
+  assert.match(s, /closer/, 'must name the real remaining risk (a rationale containing the closer)');
+});
+
+test('SKILL.md hard-gates the leak case instead of merely mentioning it', () => {
+  const s = skill();
+  const step2 = s.slice(s.indexOf('### 2.'), s.indexOf('### 3.'));
+  assert.match(step2, /leak_warning/);
+  assert.match(step2, /STOPP|stopp/, 'step 2 must stop the ritual, not just report');
+  assert.match(step2, /\.gitignore/, 'step 2 must name the remedy');
+});
+
 test('SKILL.md routes the next session via the repo-mailbox route skill', () => {
   assert.match(skill(), /repo-mailbox:route/);
 });