Initial commit: cert-manager API server

FastAPI-based SSL certificate automation server.
- Google Public CA wildcard cert issuance via certbot
- Cloudflare DNS-01 challenge with auto EAB key generation
- APISIX multi-instance deployment with domain-instance mapping
- Vault integration for all secrets
- Bearer token auth, retry logic, Discord DM alerts
- Auto-renewal scheduler (daily 03:00 UTC)

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

app/cloudflare.py

@@ -0,0 +1,37 @@
+import httpx
+
+from .config import AppConfig
+
+
+async def list_domains(config: AppConfig) -> list[dict]:
+    """Cloudflare API로 zone 목록 조회."""
+    headers = {
+        "Authorization": f"Bearer {config.cloudflare_api_token}",
+        "Content-Type": "application/json",
+    }
+    zones = []
+    page = 1
+
+    async with httpx.AsyncClient(timeout=30) as client:
+        while True:
+            resp = await client.get(
+                "https://api.cloudflare.com/client/v4/zones",
+                headers=headers,
+                params={"page": page, "per_page": 50},
+            )
+            resp.raise_for_status()
+            data = resp.json()
+
+            for zone in data["result"]:
+                zones.append({
+                    "id": zone["id"],
+                    "name": zone["name"],
+                    "status": zone["status"],
+                })
+
+            info = data.get("result_info", {})
+            if page >= info.get("total_pages", 1):
+                break
+            page += 1
+
+    return zones