Rename the import package app to fluksio

A wheel whose top-level module is `app` collides with anything else in a
user's venv, so the package that is about to be published takes the name
it is published under. Only the Python package moves; the repo, the
Docker WORKDIR and the compose project keep theirs.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

backend/fluksio/flow/nodes/ntfy.py

@@ -0,0 +1,87 @@
+"""Ntfy: push a notification to a phone.
+
+The flow-level counterpart to the engine's own alerting — this is a flow
+deciding something is worth saying, rather than the engine reporting that it
+broke.
+"""
+
+from __future__ import annotations
+
+import logging
+from collections.abc import Iterable
+from typing import Any
+
+from pydantic import BaseModel, ConfigDict, Field
+
+from fluksio.flow.messages import MessageSpec
+from fluksio.flow.nodes.base import Node
+from fluksio.flow.nodes.http import shared_client
+
+logger = logging.getLogger(__name__)
+
+
+class NtfyNode(Node):
+    """Publish an incoming value as a notification on an ntfy topic."""
+
+    # A notification sent twice is read twice.
+    idempotent = False
+
+    class Params(BaseModel):
+        model_config = ConfigDict(extra="allow")
+
+        server: str = Field(
+            default="https://ntfy.sh", description="Base URL of the ntfy server."
+        )
+        topic: str = Field(description="Topic to publish to.")
+        title: str = Field(default="", description="Notification title.")
+        priority: str = Field(
+            default="default",
+            description="min, low, default, high or urgent.",
+        )
+        tags: str = Field(default="", description="Comma-separated ntfy tags.")
+        token: str = Field(
+            default="",
+            description="Access token, for a server that needs one.",
+            json_schema_extra={"x-secret": True},
+        )
+        timeout: float = Field(default=10.0, gt=0)
+
+    __slots__ = ("cfg",)
+
+    def __init__(
+        self,
+        requires: MessageSpec | Iterable[MessageSpec] = (),
+        provides: MessageSpec | Iterable[MessageSpec] = (),
+        params: dict[str, Any] | None = None,
+        name: str | None = None,
+    ):
+        self.cfg = self.Params.model_validate(params or {})
+        super().__init__(
+            f=self._notify,
+            requires=requires,
+            provides=provides,
+            params=params,
+            name=name or "ntfy",
+        )
+
+    def _notify(self, params: dict[str, Any], **kwargs: Any) -> dict[str, Any] | None:
+        if not kwargs:
+            return None
+        body = str(next(iter(kwargs.values())))
+
+        headers = {"Priority": self.cfg.priority}
+        if self.cfg.title:
+            headers["Title"] = self.cfg.title
+        if self.cfg.tags:
+            headers["Tags"] = self.cfg.tags
+        if self.cfg.token:
+            headers["Authorization"] = f"Bearer {self.cfg.token}"
+
+        response = shared_client().post(
+            f"{self.cfg.server.rstrip('/')}/{self.cfg.topic}",
+            content=body.encode(),
+            headers=headers,
+            timeout=self.cfg.timeout,
+        )
+        response.raise_for_status()
+        return None