feat: extract shared infrastructure from shared_lib

Phase 1-3 of decoupling plan:
- Shared DB, models, infrastructure, browser, config, utils
- Event infrastructure (domain_events outbox, bus, processor)
- Structured logging
- Generic container concept (container_type/container_id)
- Alembic migrations for all schema changes

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

browser/app/payments/__init__.py

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+

browser/app/payments/sumup.py

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+from __future__ import annotations
+
+import os
+from typing import Any, Dict, TYPE_CHECKING
+
+import httpx
+from quart import current_app
+
+from shared.config import config
+
+if TYPE_CHECKING:
+    from cart.models.order import Order
+
+SUMUP_BASE_URL = "https://api.sumup.com/v0.1"
+
+
+def _sumup_settings() -> Dict[str, str]:
+    cfg = config()
+    sumup_cfg = cfg.get("sumup", {}) or {}
+    api_key_env = sumup_cfg.get("api_key_env", "SUMUP_API_KEY")
+    api_key = os.getenv(api_key_env)
+    if not api_key:
+        raise RuntimeError(f"Missing SumUp API key in environment variable {api_key_env}")
+
+    merchant_code = sumup_cfg.get("merchant_code")
+    prefix = sumup_cfg.get("checkout_prefix", "")
+    if not merchant_code:
+        raise RuntimeError("Missing 'sumup.merchant_code' in app-config.yaml")
+
+    currency = sumup_cfg.get("currency", "GBP")
+
+    return {
+        "api_key": api_key,
+        "merchant_code": merchant_code,
+        "currency": currency,
+        "checkout_reference_prefix": prefix,
+    }
+
+
+async def create_checkout(
+    order: Order,
+    redirect_url: str,
+    webhook_url: str | None = None,
+    description: str | None = None,
+) -> Dict[str, Any]:
+    settings = _sumup_settings()
+    # Use stored reference if present, otherwise build it
+    checkout_reference = order.sumup_reference or f"{settings['checkout_reference_prefix']}{order.id}"
+
+    payload: Dict[str, Any] = {
+        "checkout_reference": checkout_reference,
+        "amount": float(order.total_amount),
+        "currency": settings["currency"],
+        "merchant_code": settings["merchant_code"],
+        "description": description or f"Order {order.id} at {current_app.config.get('APP_TITLE', 'Rose Ash')}",
+        "return_url": webhook_url or redirect_url,
+        "redirect_url": redirect_url,
+        "hosted_checkout": {"enabled": True},
+    }
+    headers = {
+        "Authorization": f"Bearer {settings['api_key']}",
+        "Content-Type": "application/json",
+    }
+
+    # Optional: log for debugging
+    current_app.logger.info(
+        "Creating SumUp checkout %s for Order %s amount %.2f",
+        checkout_reference,
+        order.id,
+        float(order.total_amount),
+    )
+
+    async with httpx.AsyncClient(timeout=15.0) as client:
+        resp = await client.post(f"{SUMUP_BASE_URL}/checkouts", json=payload, headers=headers)
+
+        if resp.status_code == 409:
+            # Duplicate checkout — retrieve the existing one by reference
+            current_app.logger.warning(
+                "SumUp duplicate checkout for ref %s order %s, fetching existing",
+                checkout_reference,
+                order.id,
+            )
+            list_resp = await client.get(
+                f"{SUMUP_BASE_URL}/checkouts",
+                params={"checkout_reference": checkout_reference},
+                headers=headers,
+            )
+            list_resp.raise_for_status()
+            items = list_resp.json()
+            if isinstance(items, list) and items:
+                return items[0]
+            if isinstance(items, dict) and items.get("items"):
+                return items["items"][0]
+            # Fallback: re-raise original error
+            resp.raise_for_status()
+
+        if resp.status_code >= 400:
+            current_app.logger.error(
+                "SumUp checkout error for ref %s order %s: %s",
+                checkout_reference,
+                order.id,
+                resp.text,
+            )
+        resp.raise_for_status()
+        data = resp.json()
+
+    return data
+
+
+async def get_checkout(checkout_id: str) -> Dict[str, Any]:
+    """Fetch checkout status/details from SumUp."""
+    settings = _sumup_settings()
+    headers = {
+        "Authorization": f"Bearer {settings['api_key']}",
+        "Content-Type": "application/json",
+    }
+
+    async with httpx.AsyncClient(timeout=10.0) as client:
+        resp = await client.get(f"{SUMUP_BASE_URL}/checkouts/{checkout_id}", headers=headers)
+        resp.raise_for_status()
+        return resp.json()