Touch is a panel setting, and the rail grows with it

It described the wrong object. A dashboard is a document that may hang on a
hallway tablet and in a desk browser at the same time, and only one of those
has fingers on it — so the flag moves off `DashboardDef.settings` and onto
`PanelDef` as a plain bool, ticked in the Panels dialog. `useCanvasRoot` takes
it as an argument rather than reading the document, and `/panel/{id}` is the
only surface with a panel to ask.

Dropping the message binding with it is deliberate: nothing drove it, and a
flow deciding whether a screen has fingers on it was never the point. A stored
`settings.touch` is inert rather than migrated, which `_check_settings`
skipping unknown names already guaranteed.

The rail was the other half. It had no touch behaviour at all and its 40px
buttons met neither branch of the 44/32 rule. `[data-touch] .dui-rail{-item}`
in `ui/core/core.css` spends the padding and the gap on the buttons instead,
so they reach the 44px target and the rail comes out taller at exactly the
same width — `RAIL_INSET` never moves, and the arrangement under it does not
either.

Also closes the panels-dialog icon gap: `DashboardSummary` carries the `icon`
now, so the dialog draws each assigned dashboard's rail glyph beside its
checkbox. `initials()` went from three identical copies in the looks to one in
`Dashboard/icons.ts`, so the dialog and the rail fall back the same way.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Va7ExQDtuwKN7kNpHhWWNQ

backend/fluksio/flow/dashboards.py

@@ -143,8 +143,6 @@ SETTING_DTYPES: dict[str, str] = {
     # An image drawn under the widgets, by URL. A flow publishing to it is what
     # a wallpaper that changes looks like here.
     "background": "str",
-    # Bigger controls and no hover states, for a panel that is touched.
-    "touch": "bool",
 }
 
 
@@ -525,6 +523,9 @@ class DashboardSummary(BaseModel):
 
     name: str
     title: str = ""
+    #: The glyph this dashboard draws on a panel's rail, so a list can show it
+    #: without reading every document.
+    icon: str = ""
     widget_count: int = 0
     has_draft: bool = False
     #: Of the working copy, so publishing from a list needs no second read.
@@ -586,6 +587,7 @@ class DashboardStore:
                 DashboardSummary(
                     name=defn.name,
                     title=defn.title,
+                    icon=defn.icon,
                     widget_count=len(defn.widgets),
                     has_draft=defn.has_draft,
                     version=defn.version,

backend/fluksio/flow/panels.py

@@ -31,6 +31,11 @@ class PanelDef(BaseModel):
     #: 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)
+    #: Bigger controls, a bigger rail and no hover states, for a screen that is
+    #: touched rather than pointed at. It belongs to the device rather than to
+    #: any dashboard: the same dashboard may hang on a hallway tablet and on a
+    #: desk browser, and only one of them has fingers on it.
+    touch: bool = False
     #: Which generation of credential this panel honours. A token names the
     #: nonce it was minted at, so bumping this refuses the screen currently
     #: hanging here and leaves the panel, its dashboards and their arrangement