feat: let a user_id ticket carry an email, accept frontend_url

`CreateTicket` no longer rejects `user_id` together with `name`/`email`
(the exclusion was a fork-only dispatch convenience from dfabcb8; nothing
needed it). `crud.create_ticket` stops blanking name/email when a user_id
is present, so logged-in webapp buyers can have their ticket emailed —
until now `_send_ticket_notification` short-circuited on the empty
address for every app purchase.

New optional `frontend_url` (absolute http(s) root, no query/fragment/..,
trailing slash stripped) lets a buyer-side client name the app the buyer
should be returned to and linked into from the ticket email; the origin
allow-list lives in views_api.

Also folds in the pending black reflow of migrations_fork.py.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYwoAkZZmXMMmaBp4WGUBo

models.py

@@ -1,8 +1,11 @@
 import json
 from datetime import datetime
+from urllib.parse import urlsplit
 
 from pydantic import BaseModel, EmailStr, Field, root_validator, validator
 
+PAYMENT_METHODS = ("lightning", "fiat")
+
 
 class PromoCode(BaseModel):
     code: str
@@ -28,6 +31,26 @@ class EventExtra(BaseModel):
     nostr_notifications: bool = False
     notification_subject: str = ""
     notification_body: str = ""
+    # Rails the organizer accepts for this event. Empty = legacy rule
+    # ("lightning" always, "fiat" when allow_fiat) — see
+    # `effective_payment_methods`. Same field name/shape as upstream v2 so the
+    # eventual rebase (#33) merges cleanly.
+    payment_methods: list[str] = Field(default_factory=list)
+
+    @validator("payment_methods", pre=True)
+    def normalize_payment_methods(cls, v):
+        if not v:
+            return []
+        if isinstance(v, str):
+            v = v.split(",")
+        seen: list[str] = []
+        for method in v:
+            method = str(method).strip().lower()
+            if method not in PAYMENT_METHODS:
+                raise ValueError(f"Unsupported payment method: {method}")
+            if method not in seen:
+                seen.append(method)
+        return seen
 
 
 class CreateEvent(BaseModel):
@@ -107,6 +130,22 @@ class PublicEvent(BaseModel):
         return v or []
 
 
+def effective_payment_methods(event: "Event | PublicEvent | CreateEvent") -> list[str]:
+    """Rails a buyer may pick for `event`.
+
+    Explicit `extra.payment_methods` wins; an empty list falls back to the
+    pre-#payment-methods rule so events created before the field existed
+    keep behaving the same (Lightning always, fiat iff `allow_fiat`).
+    """
+    explicit = list(getattr(event.extra, "payment_methods", []) or [])
+    if explicit:
+        return explicit
+    methods = ["lightning"]
+    if event.allow_fiat:
+        methods.append("fiat")
+    return methods
+
+
 class EventsSettings(BaseModel):
     """Extension-level settings for the events extension."""
 
@@ -136,16 +175,37 @@ class CreateTicket(BaseModel):
     # Number of tickets to buy on this single invoice. Bounded so a
     # bad client can't run away with the organizer's capacity.
     quantity: int = Field(default=1, ge=1, le=10)
+    # App root of the client that is buying (e.g. https://app.example/events).
+    # The extension builds the Stripe success/cancel URLs and the emailed
+    # ticket link under it, so the buyer lands back in the app they came
+    # from. Origin is allow-listed server-side (see `_resolve_frontend_root`);
+    # absent = today's behaviour (the LNbits host).
+    frontend_url: str | None = Field(default=None, max_length=512)
+
+    @validator("frontend_url")
+    def validate_frontend_url(cls, v):
+        if v is None:
+            return None
+        v = v.strip()
+        if not v:
+            return None
+        parts = urlsplit(v)
+        if parts.scheme not in ("http", "https") or not parts.netloc:
+            raise ValueError("frontend_url must be an absolute http(s) URL")
+        if parts.query or parts.fragment or ".." in parts.path:
+            raise ValueError("frontend_url must not contain a query, fragment or '..'")
+        return v.rstrip("/")
 
     @root_validator
     def validate_identifiers(cls, values):
+        """A ticket needs an identity: an LNbits `user_id`, or `name` +
+        `email` for guests. A logged-in buyer may add `email` (and `name`)
+        on top of `user_id` so the ticket can be emailed to them."""
         name = values.get("name")
         email = values.get("email")
         user_id = values.get("user_id")
         if not user_id and not (name and email):
             raise ValueError("Either user_id or both name and email must be provided")
-        if user_id and (name or email):
-            raise ValueError("Cannot provide both user_id and name/email")
         return values
 
 
@@ -168,6 +228,22 @@ class Ticket(BaseModel):
     payment_hash: str | None = None
 
 
+class NotificationDeliveryResult(BaseModel):
+    attempted: bool = False
+    sent: bool = False
+    error: str | None = None
+
+
+class TicketResendResult(BaseModel):
+    ticket: Ticket
+    email: NotificationDeliveryResult = Field(
+        default_factory=NotificationDeliveryResult
+    )
+    nostr: NotificationDeliveryResult = Field(
+        default_factory=NotificationDeliveryResult
+    )
+
+
 class PublicTicket(BaseModel):
     event: str
     name: str | None = None