feat(artist): add Share and Download actions to the Artist detail page (#5944)

* feat(ui): add Share button to artist detail page

* feat(ui): add Download button to artist detail page

* fix(ui): scope artist share/download to album-artist content

Gate the artist Share/Download actions on album-artist stats and show the
album-artist size, since ZipArtist and the share query only cover
album_artist_id songs. Previously the total (role-inclusive) size was shown
and guest-only artists could produce an empty archive. Applies to the artist
toolbar, the shared context menu, and the download dialog title.

* fix: match artist download/share to album-artist participation

ZipArtist and the artist share query filtered the deprecated album_artist_id
column, which only stores the first album artist of a track. Secondary
album-artists (co-credited but not first) got an empty download/share even
though the UI offered it. Filter by the album-artist role participation
instead, matching the artist's album-artist stats used to gate the actions.
Also cover the artist-specific size branch of the download dialog.

* fix(share): scope artist shares to the owner's libraries

The artist share query broadened to album-artist participation, which could
pull a secondary album artist's tracks from libraries the (non-admin) share
owner cannot access into the public share. Load the artist share as the owner
so their library access is applied, mirroring how playlist shares already work.
Adds a repository test covering co-album-artist inclusion and library scoping.

* test(share): assert album participation branch of artist shares

Link the co-album-artist fixtures to albums and assert share.Albums (used by
Subsonic getShares) includes the accessible album and excludes the one in a
library the owner cannot access, so the album participation + scoping branch
is covered too.

* fix: exclude missing files from artist download/share actions

An artist's stats still count files that went missing, so the toolbar/context
menu could offer Download/Share for an artist whose files are all gone, while
the share query (missing=false) returns nothing and downloads open dead paths.
Hide the actions when the artist is missing and exclude missing files from
ZipArtist, matching the share semantics.

* refactor: dedupe artist download-size and share-owner lookups

Extract the 'album-artist download size (or none when missing)' rule into a
single artistDownloadSize() helper shared by the toolbar, context menu, and
download dialog, and factor the duplicated share-owner context lookup into a
shareRepository.ownerContext() method used by both the artist and playlist
share cases.

* refactor(ui): move artistDownloadSize helper to common

utils is for domain-agnostic, potentially portable code; this helper is
Navidrome-specific (artist stats shape), so it belongs in common. Consumers
import it directly from common/artist to avoid pulling in the common barrel.

ui/src/dialogs/DownloadMenuDialog.jsx

@@ -8,8 +8,9 @@ import {
   DialogTitle,
 } from '@material-ui/core'
 import subsonic from '../subsonic'
-import { closeDownloadMenu } from '../actions'
+import { closeDownloadMenu, DOWNLOAD_MENU_ARTIST } from '../actions'
 import { formatBytes } from '../utils'
+import { artistDownloadSize } from '../common/artist'
 import { useTranscodingOptions } from './useTranscodingOptions'
 
 const DownloadMenuDialog = () => {
@@ -22,6 +23,12 @@ const DownloadMenuDialog = () => {
   const { TranscodingOptionsInput, format, maxBitRate, originalFormat } =
     useTranscodingOptions()
 
+  // Artist downloads only include album-artist songs, so show that size
+  const downloadSize =
+    recordType === DOWNLOAD_MENU_ARTIST
+      ? artistDownloadSize(record)
+      : record?.size
+
   const handleClose = (e) => {
     dispatch(closeDownloadMenu())
     e.stopPropagation()
@@ -55,7 +62,7 @@ const DownloadMenuDialog = () => {
               smart_count: 1,
             }).toLocaleLowerCase(),
             name: record?.name || record?.title,
-            size: formatBytes(record?.size),
+            size: formatBytes(downloadSize),
           })}
       </DialogTitle>
       <DialogContent>

ui/src/dialogs/DownloadMenuDialog.test.jsx

@@ -0,0 +1,58 @@
+import * as React from 'react'
+import { TestContext } from 'ra-test'
+import { render, screen, cleanup } from '@testing-library/react'
+import { describe, afterEach, it, expect, vi } from 'vitest'
+import DownloadMenuDialog from './DownloadMenuDialog'
+import { DOWNLOAD_MENU_ALBUM, DOWNLOAD_MENU_ARTIST } from '../actions'
+
+vi.mock('./useTranscodingOptions', () => ({
+  useTranscodingOptions: () => ({
+    TranscodingOptionsInput: () => null,
+    format: '',
+    maxBitRate: 0,
+    originalFormat: true,
+  }),
+}))
+
+vi.mock('react-admin', async (importOriginal) => {
+  const actual = await importOriginal()
+  return {
+    ...actual,
+    useTranslate: () => (key, opts) =>
+      opts?.size ? `${key}:${opts.name}:${opts.size}` : key,
+  }
+})
+
+const renderDialog = (record, recordType) =>
+  render(
+    <TestContext
+      initialState={{ downloadMenuDialog: { open: true, record, recordType } }}
+    >
+      <DownloadMenuDialog />
+    </TestContext>,
+  )
+
+describe('DownloadMenuDialog', () => {
+  afterEach(cleanup)
+
+  it('shows the album-artist size (not the total) for an artist download', () => {
+    renderDialog(
+      {
+        id: 'ar1',
+        name: 'Artist',
+        size: 999999999,
+        stats: { albumartist: { size: 1024 } },
+      },
+      DOWNLOAD_MENU_ARTIST,
+    )
+    expect(screen.getByText(/:Artist:1 KB$/)).toBeInTheDocument()
+  })
+
+  it('shows the total size for an album download', () => {
+    renderDialog(
+      { id: 'al1', name: 'Album', size: 1024 * 1024 },
+      DOWNLOAD_MENU_ALBUM,
+    )
+    expect(screen.getByText(/:Album:1 MB$/)).toBeInTheDocument()
+  })
+})