fix(systems): sweeps are the discovery moment — zero-Systems hint, create_system dedup gate, prose inverted

First real-world test of the #2562 fixes (Scribe issue #2569): a Forge
session ran a whole-codebase audit and created zero Systems — endorsed
by the shipped guidance, whose "no particular area takes none" clause
read as an exemption for exactly the record type that enumerates the
subsystem vocabulary. And the systems_hint was silent for a zero-Systems
project, the one state nothing else nudges out of.

- systems_hint gains a zero-Systems branch: prompt the FIRST
  create_system instead of going quiet.
- create_system is duplicate-gated like the other creates (normalized
  name, archived included, fail-open) — liberal creation becomes safe by
  construction, so the guidance can stop preaching restraint.
- Prose inverted on every surface (hint text, create_system docstring,
  floor bullet, using-scribe step 7): audits/sweeps take several tags
  and mint the Systems they name; the gate is the guardrail against
  sprawl, not holding back; only a record genuinely about no particular
  area goes untagged.
- Plugin 0.1.26 -> 0.1.27.

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

tests/test_mcp_tool_systems.py

@@ -89,17 +89,48 @@ async def test_untagged_hint_names_the_projects_systems():
 
 
 @pytest.mark.asyncio
-async def test_untagged_hint_absent_without_systems_and_fails_open():
+async def test_untagged_hint_zero_systems_prompts_first_create_and_fails_open():
     from scribe.mcp.tools.systems import untagged_systems_hint
     with patch("scribe.mcp.tools.systems.systems_svc") as svc:
+        # Zero Systems is the state nothing else nudges out of — the hint must
+        # prompt the FIRST create_system, not go silent.
         svc.list_systems = AsyncMock(return_value=[])
-        assert await untagged_systems_hint(1, 5) is None
+        hint = await untagged_systems_hint(1, 5)
+        assert "no Systems yet" in hint and "create_system" in hint
     with patch("scribe.mcp.tools.systems.systems_svc") as svc:
         # A hint must never break a create — DB failure degrades to no hint.
         svc.list_systems = AsyncMock(side_effect=RuntimeError("db down"))
         assert await untagged_systems_hint(1, 5) is None
 
 
+@pytest.mark.asyncio
+async def test_create_system_same_normalized_name_is_duplicate_gated():
+    existing = _fake_system(sid=7, name="Scrape Pipeline")
+    existing.name = "Scrape Pipeline"
+    with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
+         patch("scribe.mcp.tools.systems.systems_svc") as svc:
+        svc.list_systems = AsyncMock(return_value=[existing])
+        svc.create_system = AsyncMock()
+        from scribe.mcp.tools.systems import create_system
+        result = await create_system(project_id=5, name="  scrape   pipeline ")
+    assert result["duplicate"] is True
+    assert result["existing_id"] == 7
+    svc.create_system.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_create_system_distinct_name_passes_the_gate():
+    other = _fake_system(sid=7, name="Workers")
+    other.name = "Workers"
+    with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
+         patch("scribe.mcp.tools.systems.systems_svc") as svc:
+        svc.list_systems = AsyncMock(return_value=[other])
+        svc.create_system = AsyncMock(return_value=_fake_system(sid=8, name="Exporter"))
+        from scribe.mcp.tools.systems import create_system
+        result = await create_system(project_id=5, name="Exporter")
+    assert result["name"] == "Exporter"
+
+
 @pytest.mark.asyncio
 async def test_create_task_untagged_in_project_with_systems_carries_hint():
     note = MagicMock(); note.id = 60; note.to_dict.return_value = {"id": 60}