refactor: unify post composition — all assets are artefacts

PostDetail now uses Artefacts exclusively for all 4 asset types:
- Caption copy = Artefact with type='copy', copy_type='caption'
- Body copy = Artefact with type='copy', copy_type='body'
- Design = Artefact with type='design'
- Video = Artefact with type='video'

Removed TranslationDetailPanel from PostDetail entirely.
Same ArtefactDetailPanel, same workflow, same version management
for all asset types. Link picker searches artefacts only.

Server: copy_type added to Artefacts schema, accepted in POST/PATCH.
post-composition.js rewritten to use Artefacts table for all pieces.
Content preview fetched from ArtefactVersionTexts.

Translations entity still exists for the standalone Copy page.

Also: version creation rules, submit-review content validation,
reviewer mandatory for translations, artefact creation simplified.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/src/pages/PostDetail.jsx

@@ -9,7 +9,6 @@ import PlatformIcon from '../components/PlatformIcon'
 import StatusBadge from '../components/StatusBadge'
 import PortalSelect from '../components/PortalSelect'
 import CommentsSection from '../components/CommentsSection'
-import TranslationDetailPanel from '../components/TranslationDetailPanel'
 import ArtefactDetailPanel from '../components/ArtefactDetailPanel'
 import { useToast } from '../components/ToastContainer'
 
@@ -45,7 +44,6 @@ export default function PostDetail() {
   const [linking, setLinking] = useState(false)
 
   // Sub-panels
-  const [openTranslation, setOpenTranslation] = useState(null)
   const [openArtefact, setOpenArtefact] = useState(null)
 
   useEffect(() => {
@@ -116,22 +114,17 @@ export default function PostDetail() {
     setActivePicker(type)
     setPickerSearch('')
     try {
-      if (type === 'caption' || type === 'body') {
-        const all = await api.get('/translations')
-        // Show all translations not already linked to THIS post
-        setLinkCandidates((Array.isArray(all) ? all : []).filter(t => {
-          const linkedTo = t.post_id || t.postId
-          return !linkedTo || String(linkedTo) !== String(id)
-        }))
-      } else {
-        const all = await api.get('/artefacts')
-        const at = type === 'video' ? 'video' : 'design'
-        setLinkCandidates((Array.isArray(all) ? all : []).filter(a => {
-          const linkedTo = a.post_id || a.postId
-          const matchesType = (a.type || 'design') === at
-          return matchesType && (!linkedTo || String(linkedTo) !== String(id))
-        }))
-      }
+      const all = await api.get('/artefacts')
+      let typeFilter
+      if (type === 'caption') typeFilter = a => a.type === 'copy' && a.copy_type === 'caption'
+      else if (type === 'body') typeFilter = a => a.type === 'copy' && (a.copy_type === 'body' || !a.copy_type)
+      else if (type === 'video') typeFilter = a => a.type === 'video'
+      else typeFilter = a => (a.type || 'design') === 'design'
+
+      setLinkCandidates((Array.isArray(all) ? all : []).filter(a => {
+        const linkedTo = a.post_id || a.postId
+        return typeFilter(a) && (!linkedTo || String(linkedTo) !== String(id))
+      }))
     } catch {
       setLinkCandidates([])
       toast.error(t('common.error'))
@@ -141,12 +134,7 @@ export default function PostDetail() {
   const handleLink = async (itemId) => {
     setLinking(true)
     try {
-      const copyType = activePicker === 'caption' || activePicker === 'body' ? activePicker : null
-      if (activePicker === 'caption' || activePicker === 'body') {
-        await api.patch(`/translations/${itemId}`, { post_id: Number(id), copy_type: copyType })
-      } else {
-        await api.patch(`/artefacts/${itemId}`, { post_id: Number(id) })
-      }
+      await api.patch(`/artefacts/${itemId}`, { post_id: Number(id) })
       toast.success(t('posts.updated'))
       setActivePicker(null)
       loadComposition()
@@ -164,8 +152,7 @@ export default function PostDetail() {
       : composition?.video
     if (!piece) return
     try {
-      const endpoint = (type === 'caption' || type === 'body') ? `/translations/${piece.id}` : `/artefacts/${piece.id}`
-      await api.patch(endpoint, { post_id: null })
+      await api.patch(`/artefacts/${piece.id}`, { post_id: null })
       toast.success(t('posts.updated'))
       loadComposition()
     } catch {
@@ -179,39 +166,25 @@ export default function PostDetail() {
       : type === 'design' ? composition?.design
       : composition?.video
     if (!piece) return
-    if (type === 'caption' || type === 'body') {
-      try {
-        const full = await api.get(`/translations/${piece.id}`)
-        setOpenTranslation(full)
-      } catch { toast.error(t('common.saveFailed')) }
-    } else {
-      try {
-        const full = await api.get(`/artefacts/${piece.id}`)
-        setOpenArtefact(full)
-      } catch { toast.error(t('common.saveFailed')) }
-    }
+    try {
+      const full = await api.get(`/artefacts/${piece.id}`)
+      setOpenArtefact(full)
+    } catch { toast.error(t('common.saveFailed')) }
   }
 
   const handleCreate = async (type) => {
-    const isCopy = type === 'caption' || type === 'body'
+    const label = type === 'caption' ? t('postDetail.captionCopy')
+      : type === 'body' ? t('postDetail.bodyCopy')
+      : type === 'design' ? t('postDetail.design')
+      : t('postDetail.video')
     try {
-      if (isCopy) {
-        const created = await api.post('/translations', {
-          title: `${title} — ${type === 'caption' ? t('postDetail.captionCopy') : t('postDetail.bodyCopy')}`,
-          source_language: 'AR',
-          source_content: '',
-          post_id: Number(id),
-          copy_type: type,
-        })
-        setOpenTranslation(created)
-      } else {
-        const created = await api.post('/artefacts', {
-          title: `${type === 'design' ? t('postDetail.design') : t('postDetail.video')} — ${title}`,
-          type: type,
-          post_id: Number(id),
-        })
-        setOpenArtefact(created)
-      }
+      const created = await api.post('/artefacts', {
+        title: `${label} — ${title}`,
+        type: type === 'caption' || type === 'body' ? 'copy' : type,
+        copy_type: type === 'caption' ? 'caption' : type === 'body' ? 'body' : undefined,
+        post_id: Number(id),
+      })
+      setOpenArtefact(created)
       loadComposition()
     } catch (err) {
       toast.error(t('common.saveFailed'))
@@ -452,16 +425,6 @@ export default function PostDetail() {
       </div>
 
       {/* ─── SUB-PANELS (they render their own SlidePanel internally) ─── */}
-      {openTranslation && (
-        <TranslationDetailPanel
-          translation={openTranslation}
-          onClose={() => { setOpenTranslation(null); loadComposition() }}
-          onUpdate={loadComposition}
-          onDelete={() => { setOpenTranslation(null); loadComposition() }}
-          assignableUsers={teamMembers}
-        />
-      )}
-
       {openArtefact && (
         <ArtefactDetailPanel
           artefact={openArtefact}