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>

src/scribe/mcp/tools/rulebooks.py

@@ -604,7 +604,12 @@ async def rule_history(rule_id: int, version_id: int = 0) -> dict:
     versions = await rulebooks_svc.list_rule_versions(rule_id, uid)
     if versions is None:
         raise ValueError(f"rule {rule_id} not found")
-    rule = await rulebooks_svc.get_rule(rule_id, uid)
+    # Fail-open, like the deletes: a missing title must not turn a readable
+    # history into an error.
+    try:
+        rule = await rulebooks_svc.get_rule(rule_id, uid)
+    except Exception:
+        rule = None
     return {
         "rule_id": rule_id,
         "title": rule.title if rule else "",