fix(deslop-shared-libs): probe the audited repository with -C <repo>

A CI run probed safe-git from the session directory above the target repo, so
the capability probe never touched the repository and the run fell back to the
API without a local attempt. The probe (and any call from elsewhere) now names
the audited repository.

test/shared-libs-fixture.test.ts

@@ -36,7 +36,7 @@ describe('shared-code Git guard', () => {
     installSourceShims(f);
     const instructions = fs.readFileSync(standaloneInstructions(f), 'utf8');
     const helper = path.join(SHARED_LIBS_ROOT, 'bin/gstack-safe-git');
-    expect(instructions).toContain(`\`${helper} rev-parse --is-inside-work-tree\``);
+    expect(instructions).toContain(`\`${helper} -C <repo> rev-parse --is-inside-work-tree\``);
     expect(instructions).not.toContain('~/.claude/skills/gstack');
     const run = (command: string, args: string[]) => spawnSync(command, args, {
       cwd: f.repo, encoding: 'utf8', timeout: 10_000, env: { ...process.env, ...f.env } });

test/shared-libs-rendering.test.ts

@@ -56,7 +56,7 @@ describe('shared-code skill distribution', () => {
       expect(standalone).toContain('Keep API responses and intermediate data on stdout or in memory');
       // Git safety is the installed helper from the trusted global runtime, not a retyped prefix.
       const safeGit = `~/${host.globalRoot}/bin/gstack-safe-git`;
-      expect(standalone).toContain(`${safeGit} rev-parse --is-inside-work-tree`);
+      expect(standalone).toContain(`${safeGit} -C <repo> rev-parse --is-inside-work-tree`);
       expect(standalone).toContain(`${safeGit} ls-files --cached --others --exclude-standard -z`);
       expect(standalone).toContain('never bare `git`');
       expect(standalone).not.toContain('git --no-pager');