chore: fix assets install - use hash

install/install.nu

@@ -112,10 +112,35 @@ def main [] {
   }
 
   mkdir $data_dir
-  cp -r $templates_src $"($data_dir)/templates"
-  cp -r $public_src    $"($data_dir)/public"
 
-  print $"✓ assets         ($data_dir)/"
+  let asset_dirs = [$templates_src $public_src]
+  mut updated = 0
+  mut skipped = 0
+
+  for asset_dir in $asset_dirs {
+    let dir_name = ($asset_dir | path basename)
+    let dest_base = $"($data_dir)/($dir_name)"
+    mkdir $dest_base
+    for src_file in (glob $"($asset_dir)/**/*" | where { |f| ($f | path type) == "file" }) {
+      let rel   = ($src_file | str replace $"($asset_dir)/" "")
+      let dest_file = $"($dest_base)/($rel)"
+      let dest_parent = ($dest_file | path dirname)
+      mkdir $dest_parent
+      let needs_update = if ($dest_file | path exists) {
+        (open --raw $src_file | hash sha256) != (open --raw $dest_file | hash sha256)
+      } else {
+        true
+      }
+      if $needs_update {
+        cp $src_file $dest_file
+        $updated = $updated + 1
+      } else {
+        $skipped = $skipped + 1
+      }
+    }
+  }
+
+  print $"✓ assets         ($data_dir)/  updated=($updated) unchanged=($skipped)"
 
   # ── 5. Config skeleton + global NATS topology ─────────────────────────────
   let streams_default = $"($repo_root)/install/resources/streams.json"