fix(scribe): a delete must not depend on the lookup that names it (#3273)

CI caught the naming work reaching for Postgres from the unit lane, and the
connection error was the symptom of a real design fault rather than a test
gap: reading the title BEFORE the delete put a live query on the delete path,
so a lookup that failed would have stopped the delete happening.

That is a decoration breaking its payload — the same mistake just fixed in
rules_etag, made again two commits later. Every title lookup now fails open:
delete_task, delete_note, delete_milestone, delete_snippet and rule_history
lose the name, never the operation.

The five unit tests mock the lookup rather than reaching for a database, and
delete_note gains one asserting the delete still happens when the lookup
raises — the behaviour, not just the absence of a crash.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_mcp_tool_snippets.py

@@ -138,9 +138,18 @@ async def test_merge_snippets_read_only_target_says_why():
 @pytest.mark.asyncio
 async def test_delete_snippet_retires_or_raises():
     from scribe.mcp.tools.snippets import delete_snippet
-    with patch("scribe.services.snippets.delete_snippet", AsyncMock(return_value=True)):
-        assert await delete_snippet(1) == {"deleted": True, "id": 1}
-    with patch("scribe.services.snippets.delete_snippet", AsyncMock(return_value=False)):
+
+    doomed = MagicMock()
+    doomed.title = "debounce helper"
+    # The confirmation names what went (#3273) — after the delete there is
+    # nothing left to look the title up from.
+    with patch("scribe.services.snippets.delete_snippet", AsyncMock(return_value=True)), \
+         patch("scribe.services.snippets.get_snippet", AsyncMock(return_value=doomed)):
+        assert await delete_snippet(1) == {
+            "deleted": True, "id": 1, "title": "debounce helper",
+        }
+    with patch("scribe.services.snippets.delete_snippet", AsyncMock(return_value=False)), \
+         patch("scribe.services.snippets.get_snippet", AsyncMock(return_value=None)):
         with pytest.raises(ValueError):
             await delete_snippet(404)