fix(test): unbreak gemini-namespacing test after #2790 skill consolidation (#2886)

Closes #2876 follow-up — CI on main fails because the punctuation test
in tests/gemini-namespacing.test.cjs hardcoded `/gsd-scan` as a known
command, but #2824 (consolidate 86 → 59 skills) removed scan.md from
commands/gsd/. The roster now correctly returns "scan is unknown, leave
unchanged" — the conversion is right, the test fixture is stale.

Swap `scan` for `health` in the punctuation test. Both are bedrock
commands; the test still exercises the original intent (period vs
exclamation handling on adjacent slash commands).

Note added so the next consolidation reviewer knows the swap pattern.

`npm test`: 5936/5936 pass.

tests/gemini-namespacing.test.cjs

@@ -93,8 +93,12 @@ describe('Gemini Slash Command Namespacing (Regex)', () => {
   });
 
   test('converts commands ending with punctuation', () => {
-    const input = 'Run /gsd-help. Or /gsd-scan!';
-    const expected = 'Run /gsd:help. Or /gsd:scan!';
+    // Use two stable, foundational commands so this test doesn't drift when
+    // the roster gets consolidated (cf. #2790, which removed `scan`). `help`
+    // and `health` are both bedrock; if either ever gets removed, swap to
+    // any other entry currently in commands/gsd/.
+    const input = 'Run /gsd-help. Or /gsd-health!';
+    const expected = 'Run /gsd:help. Or /gsd:health!';
     assert.strictEqual(convertSlashCommandsToGeminiMentions(input), expected);
   });