Move payments admin from events to cart service

Payments config (SumUp credentials per page) is a cart concern since all
checkouts go through the cart service. Moves it from events.rose-ash.com
to cart.rose-ash.com/<page_slug>/admin/payments/ and adds a cart admin
overview page at /<page_slug>/admin/.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cart/sexp/sexp_components.py

@@ -721,3 +721,126 @@ async def render_checkout_error_page(ctx: dict, error: str | None = None, order:
     filt = _checkout_error_filter_html()
     content = _checkout_error_content_html(error, order)
     return full_page(ctx, header_rows_html=hdr, filter_html=filt, content_html=content)
+
+
+# ---------------------------------------------------------------------------
+# Page admin (/<page_slug>/admin/)
+# ---------------------------------------------------------------------------
+
+def _cart_page_admin_header_html(ctx: dict, page_post: Any, *, oob: bool = False) -> str:
+    """Build the page-level admin header row."""
+    from quart import url_for
+    link_href = url_for("page_admin.admin")
+    return render("menu-row", id="page-admin-row", level=2, colour="sky",
+                  link_href=link_href, link_label="admin", icon="fa fa-cog",
+                  child_id="page-admin-header-child", oob=oob)
+
+
+def _cart_payments_header_html(ctx: dict, *, oob: bool = False) -> str:
+    """Build the payments section header row."""
+    from quart import url_for
+    link_href = url_for("page_admin.payments")
+    return render("menu-row", id="payments-row", level=3, colour="sky",
+                  link_href=link_href, link_label="Payments",
+                  icon="fa fa-credit-card",
+                  child_id="payments-header-child", oob=oob)
+
+
+def _cart_admin_main_panel_html(ctx: dict) -> str:
+    """Admin overview panel — links to sub-admin pages."""
+    from quart import url_for
+    payments_href = url_for("page_admin.payments")
+    return (
+        '<div id="main-panel">'
+        '<div class="flex items-center justify-between p-3 border-b">'
+        '<span class="font-medium"><i class="fa fa-credit-card text-purple-600 mr-1"></i> Payments</span>'
+        f'<a href="{payments_href}" class="text-sm underline">configure</a>'
+        '</div>'
+        '</div>'
+    )
+
+
+def _cart_payments_main_panel_html(ctx: dict) -> str:
+    """Render SumUp payment config form."""
+    from quart import url_for
+    csrf_token = ctx.get("csrf_token")
+    csrf = csrf_token() if callable(csrf_token) else (csrf_token or "")
+    page_config = ctx.get("page_config")
+    sumup_configured = bool(page_config and getattr(page_config, "sumup_api_key", None))
+    merchant_code = (getattr(page_config, "sumup_merchant_code", None) or "") if page_config else ""
+    checkout_prefix = (getattr(page_config, "sumup_checkout_prefix", None) or "") if page_config else ""
+    update_url = url_for("page_admin.update_sumup")
+
+    placeholder = "--------" if sumup_configured else "sup_sk_..."
+    input_cls = "w-full px-3 py-1.5 text-sm border border-stone-300 rounded focus:ring-purple-500 focus:border-purple-500"
+
+    return render("cart-payments-panel",
+                  update_url=update_url, csrf=csrf,
+                  merchant_code=merchant_code, placeholder=placeholder,
+                  input_cls=input_cls, sumup_configured=sumup_configured,
+                  checkout_prefix=checkout_prefix)
+
+
+# ---------------------------------------------------------------------------
+# Public API: Cart page admin
+# ---------------------------------------------------------------------------
+
+async def render_cart_admin_page(ctx: dict, page_post: Any) -> str:
+    """Full page: cart page admin overview."""
+    content = _cart_admin_main_panel_html(ctx)
+    hdr = root_header_html(ctx)
+    child = _page_cart_header_html(ctx, page_post) + _cart_page_admin_header_html(ctx, page_post)
+    hdr += render("cart-header-child-nested",
+                  outer_html=_cart_header_html(ctx), inner_html=child)
+    return full_page(ctx, header_rows_html=hdr, content_html=content)
+
+
+async def render_cart_admin_oob(ctx: dict, page_post: Any) -> str:
+    """OOB response: cart page admin overview."""
+    content = _cart_admin_main_panel_html(ctx)
+    oobs = (
+        _cart_page_admin_header_html(ctx, page_post, oob=True)
+        + render("cart-header-child-oob",
+                 inner_html=_page_cart_header_html(ctx, page_post)
+                 + _cart_page_admin_header_html(ctx, page_post))
+        + _cart_header_html(ctx, oob=True)
+        + root_header_html(ctx, oob=True)
+    )
+    return oob_page(ctx, oobs_html=oobs, content_html=content)
+
+
+# ---------------------------------------------------------------------------
+# Public API: Cart payments admin
+# ---------------------------------------------------------------------------
+
+async def render_cart_payments_page(ctx: dict, page_post: Any) -> str:
+    """Full page: payments config."""
+    content = _cart_payments_main_panel_html(ctx)
+    hdr = root_header_html(ctx)
+    admin_hdr = _cart_page_admin_header_html(ctx, page_post)
+    payments_hdr = _cart_payments_header_html(ctx)
+    child = _page_cart_header_html(ctx, page_post) + admin_hdr + payments_hdr
+    hdr += render("cart-header-child-nested",
+                  outer_html=_cart_header_html(ctx), inner_html=child)
+    return full_page(ctx, header_rows_html=hdr, content_html=content)
+
+
+async def render_cart_payments_oob(ctx: dict, page_post: Any) -> str:
+    """OOB response: payments config."""
+    content = _cart_payments_main_panel_html(ctx)
+    admin_hdr = _cart_page_admin_header_html(ctx, page_post)
+    payments_hdr = _cart_payments_header_html(ctx)
+    oobs = (
+        _cart_payments_header_html(ctx, oob=True)
+        + render("cart-header-child-oob",
+                 inner_html=_page_cart_header_html(ctx, page_post)
+                 + admin_hdr + payments_hdr)
+        + _cart_header_html(ctx, oob=True)
+        + root_header_html(ctx, oob=True)
+    )
+    return oob_page(ctx, oobs_html=oobs, content_html=content)
+
+
+def render_cart_payments_panel(ctx: dict) -> str:
+    """Render the payments config panel for PUT response."""
+    return _cart_payments_main_panel_html(ctx)