Add per-adventure "Sync from library" for scripts

Adventure scripts are frozen snapshots taken at creation. Add an opt-in
way to pull the latest library code into a live adventure:

- AdventureScript.source_script_id links a copy to its library Script
  (migration 24; set at adventure creation)
- list endpoint flags out_of_date by diffing copy vs library
- POST /adventures/{id}/scripts/{sid}/sync overwrites the copy's code,
  preserving enabled/position/script_state
- legacy copies with no link fall back to a name match, then adopt the link
- Play page shows a Sync button only when a copy differs from its library

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TEpWMjnfPqzZ13nPMoGhs5

frontend/src/pages/Play.jsx

@@ -298,11 +298,24 @@ function ScriptsPanel({ advId }) {
     api.listAdventureScripts(advId).then(setScripts).catch(() => setScripts([]))
   }, [advId])
 
+  const [syncingId, setSyncingId] = useState(null)
+
   const toggle = async (script) => {
     const updated = await api.updateAdventureScript(advId, script.id, { enabled: !script.enabled })
     setScripts((prev) => prev.map((s) => (s.id === script.id ? updated : s)))
   }
 
+  // Pull the latest code from the library script this copy was made from.
+  const sync = async (script) => {
+    setSyncingId(script.id)
+    try {
+      const updated = await api.syncAdventureScript(advId, script.id)
+      setScripts((prev) => prev.map((s) => (s.id === script.id ? updated : s)))
+    } finally {
+      setSyncingId(null)
+    }
+  }
+
   // Download as an import-compatible bundle (matches /scripts export), so demo
   // scripts can be forked into your own library via the Scripts page's Import.
   const download = (s) => {
@@ -341,6 +354,16 @@ function ScriptsPanel({ advId }) {
                 <span>{s.name}</span>
               </label>
               <div style={{ display: 'flex', gap: 12, flexShrink: 0 }}>
+                {s.out_of_date && (
+                  <button
+                    className="linklike"
+                    title="Replace this adventure's copy with the latest from your script library"
+                    disabled={syncingId === s.id}
+                    onClick={() => sync(s)}
+                  >
+                    {syncingId === s.id ? 'Syncing…' : '⟳ Sync from library'}
+                  </button>
+                )}
                 <button className="linklike" onClick={() => setOpenId(open ? null : s.id)}>
                   {open ? 'Hide code' : 'View code'}
                 </button>