Mixed external+note entity tab hides note Markdown behind URL-only card #1623

Summary

Opening a single entity tab for an entity typed both external and note shows the external URL links but hides the note's actual Markdown body. The tab should present both: clickable external URLs and the note's rendered content, without falling back to a dump of internal metadata. This is distinct from the completed external-only URL card (#250) and multi-type note composition (#1164/#1171).

Root Cause

features/Phantom.Workspaces/ViewModels/EntityWorkspaceTabViewModel.cs:37-48 creates the single-tab card with cardViewName: this.entityCardViewResolver.ResolveViewName(this.Entity). That resolver gives any external-typed entity precedence, regardless of its other types (features/Phantom.Workspaces/ViewModels/EntityCardViewResolver.cs:7-16):

if (!string.Equals(requestedViewName, RawViewName, System.StringComparison.Ordinal)
    && entity.IsEntityType("external"))
{
    return "external";
}
return RawViewName;

features/Phantom.Workspaces/ViewModels/EntityCardViewModel.cs:63-94 then creates ExternalCard when cardViewName == "external". The normal field editors can still be built from all non-abstract types (EntityCardViewModel.cs:581-591); the note type view declares an inline content field (features/Phantom.Workspaces.Data.Core/JsonEntities/entity-type-views/note-entity-type-view.json:7-12). But features/Phantom.Workspaces/Controls/EntityCardControl.axaml:126-130 makes these presentations mutually exclusive:

<ItemsControl ItemsSource="{Binding FieldEditors}"
              IsVisible="{Binding ExternalCard, Converter={x:Static ObjectConverters.IsNull}}" />
<ContentControl Content="{Binding ExternalCard}"
                IsVisible="{Binding ExternalCard, Converter={x:Static ObjectConverters.IsNotNull}}" />

Thus a populated ExternalCard hides the note editor entirely; the external template at features/Phantom.Workspaces/Templates/WorkspaceDataTemplates.axaml:492-506 iterates Urls only. The existing note editor is not a plain text field: tests show content.default contains a text/markdown MIME attachment with content.text, and MarkdownMimeAttachmentFieldEditorViewModel renders that text via WorkspaceMarkdownView (WorkspaceDataTemplates.axaml:349-396).

Affected Files

Design / Fix

Keep the explicit raw request authoritative. Otherwise identify external and note before the existing external-only branch (e.g. return a dedicated external-note view name). Make the card produce its existing ExternalEntityCardViewModel URL links and the curated note content editor, and allow both controls to be visible in that composite mode. Reuse FieldEditorFactory and the note type view's inline content path / existing Markdown MIME editor; do not read an invented top-level body field, show raw metadata, duplicate the Markdown, or convert URL buttons into plain text.

if (requestedViewName == RawViewName) return RawViewName;
if (entity.IsEntityType("external") && entity.IsEntityType("note")) return "external-note";
if (entity.IsEntityType("external")) return "external";
return RawViewName;
// In the common card: construct ExternalCard for external AND external-note;
// show FieldEditors for raw AND external-note, not for external-only.

Leave the pure external URL-only behavior (#250), pure note Markdown behavior (#1171), and explicit raw view unchanged. Because the entity tab and other card hosts reuse EntityCardControl, make the composite behavior consistent wherever a non-raw card is resolved; note the entity browser and ViewEntityViewModel explicitly request raw (EntityBrowserWorkspaceTabViewModel.cs:203,365, ViewEntityViewModel.cs:39) and should not be inadvertently converted. On live snapshot update rebuild both links and realized field editors, and on reopening/reloading the tab resolve the mixed type afresh. If the type set changes while the same card is open, update presentation or recreate the card instead of retaining a stale constructor-time view name. Preserve lazy editor construction on first realization.

Expected Tests