Populate the client website template with catalog feature flags.

Extract always-on public/portal/UTM plus optional email_sms, directmail, blog, payments, social, and social_ai so new client sites can be bootstrapped from this seed.

Refs #1
Refs #2

Co-authored-by: Cursor <cursoragent@cursor.com>

site/core/registry.py

@@ -0,0 +1,105 @@
+"""Optional-app registry. Apps register from AppConfig.ready() — never from always-on imports."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import Callable
+
+from django.urls import reverse
+
+
+@dataclass(frozen=True)
+class NavItem:
+    section: str
+    label: str
+    url_name: str
+    group: str = "Overview"
+    order: int = 100
+
+
+GROUP_ORDER = {
+    "Overview": 10,
+    "Outreach": 20,
+    "Content": 30,
+    "Social": 40,
+    "Billing": 50,
+}
+
+_portal_nav: list[NavItem] = []
+_public_nav: list[NavItem] = []
+_dashboard_collectors: list[Callable] = []
+_dispatchers: list[Callable] = []
+_features: set[str] = set()
+
+
+def register_feature(name: str) -> None:
+    _features.add(name)
+
+
+def enabled_features() -> frozenset[str]:
+    return frozenset(_features)
+
+
+def register_portal_nav(
+    *,
+    section: str,
+    label: str,
+    url_name: str,
+    group: str = "Overview",
+    order: int = 100,
+) -> None:
+    item = NavItem(
+        section=section, label=label, url_name=url_name, group=group, order=order
+    )
+    _portal_nav.append(item)
+
+
+def register_public_nav(
+    *,
+    section: str,
+    label: str,
+    url_name: str,
+    order: int = 100,
+) -> None:
+    _public_nav.append(
+        NavItem(section=section, label=label, url_name=url_name, order=order)
+    )
+
+
+def register_dashboard_collector(fn: Callable) -> None:
+    """fn(request) -> dict merged into dashboard home context."""
+    _dashboard_collectors.append(fn)
+
+
+def register_dispatcher(fn: Callable) -> None:
+    """fn() -> int count of items enqueued. Called by dispatch_due."""
+    _dispatchers.append(fn)
+
+
+def portal_nav() -> list[NavItem]:
+    return sorted(
+        _portal_nav,
+        key=lambda i: (GROUP_ORDER.get(i.group, 99), i.order, i.label),
+    )
+
+
+def public_nav() -> list[NavItem]:
+    return sorted(_public_nav, key=lambda i: (i.order, i.label))
+
+
+def collect_dashboard_context(request) -> dict:
+    extra: dict = {}
+    for fn in _dashboard_collectors:
+        extra.update(fn(request) or {})
+    return extra
+
+
+def run_dispatchers() -> int:
+    total = 0
+    for fn in _dispatchers:
+        total += int(fn() or 0)
+    return total
+
+
+def reverse_nav(item: NavItem) -> str:
+    return reverse(item.url_name)