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/panels.py

@@ -0,0 +1,101 @@
+"""Panels: which dashboards a given device shows.
+
+A wall tablet in the hall and one in the workshop want different dashboards,
+and the same dashboard may hang on both. Rather than nesting pages inside a
+dashboard, a panel names an ordered set of whole dashboards — each keeps its
+own canvas, its own draft and its own version, and the device switches between
+them through a rail.
+
+Stored beside the flows rather than in them, like the alerting configuration:
+which screen hangs where is the deployment's concern, not any one dashboard's.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from pydantic import BaseModel, Field, field_validator
+
+from fluksio.core.config import settings
+from fluksio.flow.dashboards import DashboardNotFound, DashboardStore
+from fluksio.flow.schemas import _validate_name
+
+
+class PanelDef(BaseModel):
+    """One device, and what it shows."""
+
+    id: str
+    title: str = ""
+    #: Ordered. The first one is what the device opens after pairing, and the
+    #: rail follows this order. A name that no longer resolves is simply a
+    #: dashboard someone deleted; the panel skips it.
+    dashboards: list[str] = Field(default_factory=list)
+
+    @field_validator("id")
+    @classmethod
+    def _check_id(cls, value: str) -> str:
+        return _validate_name(value)
+
+
+class PanelsConfig(BaseModel):
+    """Every panel this installation knows about."""
+
+    panels: list[PanelDef] = Field(default_factory=list)
+
+
+def _path() -> Path:
+    return settings.PANELS_FILE
+
+
+def read_config() -> PanelsConfig:
+    """The stored panels, or none. Blocking."""
+    path = _path()
+    if not path.exists():
+        return PanelsConfig()
+    try:
+        return PanelsConfig.model_validate_json(path.read_text())
+    except Exception:
+        # A hand-edited file that no longer parses must not lock everyone out.
+        return PanelsConfig()
+
+
+def write_config(config: PanelsConfig) -> None:
+    """Blocking."""
+    path = _path()
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(config.model_dump_json(indent=2))
+
+
+def find(panel_id: str) -> PanelDef | None:
+    """The panel by that id, or None if it was removed.
+
+    Read from disk on every call: this is what makes deleting a panel revoke
+    its credential, so it has to see the current file rather than a cache.
+    """
+    for panel in read_config().panels:
+        if panel.id == panel_id:
+            return panel
+    return None
+
+
+def messages_for(panel_id: str, store: DashboardStore) -> set[str]:
+    """Every message the widgets of this panel's dashboards read or write.
+
+    What a screen is entitled to see, as its own dashboards define it. Read
+    from the published documents, since that is what a panel draws, and empty
+    for a panel that is gone — which is the same answer as "nothing".
+    """
+    panel = find(panel_id)
+    if panel is None:
+        return set()
+    names: set[str] = set()
+    for dashboard in panel.dashboards:
+        try:
+            defn = store.read(dashboard)
+        except DashboardNotFound:
+            continue
+        for widget in defn.widgets:
+            names.update(widget.messages)
+            if widget.target:
+                names.add(widget.target)
+    return names