feat(inception): services/inception.decide() + current_defaults(); the standard Systems vocabulary moves to the service and seeds at inception (#2881, milestone 297 step 3)

- inception.decide(user, project, choices=, via=): owner-only; validates the
  choices (pure) and every target (owned rulebook / always-on for an
  exclusion / readable design system) BEFORE any effect; then, each
  idempotent: exclude always-on rulebooks, subscribe rulebooks, point the
  design system (None = explicitly none), seed the standard Systems if asked
  and the project has none; writes projects.inception LAST. Re-deciding is
  additive for exclusions/subscriptions, replaces the design system, never
  re-seeds.
- inception.current_defaults(): what binds if nobody decides — the ask's
  payload (always-on / other rulebooks, standing exclusions + subscriptions,
  design system + the choices, Systems count).
- services/systems.STANDARD_SYSTEMS (name + generic charter) + seed_standard_systems();
  mcp/tools/systems names the same list in the bootstrap ask — one vocabulary.
- Integration tests: effects land and the record says why; bad targets apply
  nothing; outsiders cannot decide.

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

src/scribe/services/systems.py

@@ -18,6 +18,41 @@ from scribe.services import access
 logger = logging.getLogger(__name__)
 
 
+# The standard cross-project vocabulary (#2798): names that mean the same
+# thing in every project, so a starter set reads the same everywhere. The
+# bootstrap ask (mcp/tools/systems) names them; the inception seed
+# (services/inception, milestone 297) mints them. Charters are deliberately
+# generic — a project refines them as its own records accrue.
+STANDARD_SYSTEMS: tuple[tuple[str, str], ...] = (
+    ("CI & Release", "How the project is verified and shipped: pipelines, runners, image/artifact builds, release tagging and rollback."),
+    ("Auth & Access", "Who may do what: identity, sessions/tokens, permissions and the scoping of every read and write to the right users."),
+    ("Data Model & Storage", "What is stored and how it is shaped: the schema, migrations, serialisation and the services that own a table's lifecycle."),
+    ("API Surface", "The doors into the capability: HTTP routes, tool/RPC surfaces, request parsing, error envelopes and their contracts."),
+    ("UI & Design", "What people see and touch: views, components, client state, and the design tokens/recipes they are built from."),
+    ("Import & Export", "Data crossing the boundary: backups, exports, imports, sync with other systems, file formats."),
+    ("Background Jobs", "Work that runs without a request: schedulers, queues, periodic ticks, retention and maintenance."),
+    ("Observability", "How the system reports on itself: logging, metrics, audit trails, health and diagnostics."),
+)
+
+
+async def seed_standard_systems(user_id: int, project_id: int) -> list[System]:
+    """Mint the standard starter set for a project that has NO Systems yet
+    (milestone 297). Idempotent: a project with any System — the vocabulary
+    already started, standard or not — gets nothing; the duplicate gate and
+    the project's own judgment take it from there. [] without write access."""
+    if await list_systems(user_id, project_id, include_archived=True):
+        return []
+    out: list[System] = []
+    for index, (name, charter) in enumerate(STANDARD_SYSTEMS):
+        system = await create_system(
+            user_id, project_id, name, description=charter, order_index=index,
+        )
+        if system is None:
+            break
+        out.append(system)
+    return out
+
+
 async def create_system(
     user_id: int,
     project_id: int,