Remove sync-name-prefix input; use bare directory name

The prefix added no functional value since syncs are already scoped
by environment (host) in Arcane. Root compose files now get the name
"root" instead of the repo name.

Author: claude

.github/actions/arcane-deploy/action.sh

@@ -16,7 +16,6 @@ AUTO_SYNC="${INPUT_AUTO_SYNC:-true}"
 SYNC_INTERVAL="${INPUT_SYNC_INTERVAL:-5}"
 TRIGGER_SYNC="${INPUT_TRIGGER_SYNC:-true}"
 ENV_VARS="${INPUT_ENV_VARS:-}"
-SYNC_NAME_PREFIX="${INPUT_SYNC_NAME_PREFIX:-${GITHUB_REPOSITORY##*/}}"
 
 # [C1/C2] Mask secrets immediately, before any logging or API calls
 [[ -n "${API_KEY}" ]] && echo "::add-mask::${API_KEY}"
@@ -167,25 +166,18 @@ discover_compose_files() {
 
 # --- Sync Naming ---
 # Derive a sync name from a compose file path.
-# "stacks/myapp/compose.yml" -> "${prefix}-myapp"
-# "compose.yml" (root) -> "${prefix}"
+# "stacks/myapp/compose.yml" -> "myapp"
+# "compose.yml" (root) -> "root"
 sync_name_from_path() {
   local path="$1"
   local dir
   dir=$(dirname "${path}")
 
-  local name
   if [[ "${dir}" == "." ]]; then
-    name="${SYNC_NAME_PREFIX}"
+    echo "root"
   else
-    name=$(basename "${dir}")
-    # Avoid "prefix-prefix" when the directory name matches the prefix
-    if [[ "${name}" != "${SYNC_NAME_PREFIX}" ]]; then
-      name="${SYNC_NAME_PREFIX}-${name}"
-    fi
+    basename "${dir}"
   fi
-
-  echo "${name}"
 }
 
 # --- Repository Management ---

.github/actions/arcane-deploy/action.yml

@@ -72,11 +72,6 @@ inputs:
     required: false
     default: 'true'
 
-  sync-name-prefix:
-    description: 'Prefix for sync names in Arcane. Defaults to the GitHub repository name.'
-    required: false
-    default: ''
-
   # Workflow environment variables
   env-vars:
     description: 'Environment variables (KEY=VALUE per line) to export to the GitHub Actions runner via $GITHUB_ENV. These are available to subsequent workflow steps, NOT inside deployed containers. Values are automatically masked in logs.'
@@ -117,5 +112,4 @@ runs:
         INPUT_AUTO_SYNC: ${{ inputs.auto-sync }}
         INPUT_SYNC_INTERVAL: ${{ inputs.sync-interval }}
         INPUT_TRIGGER_SYNC: ${{ inputs.trigger-sync }}
-        INPUT_SYNC_NAME_PREFIX: ${{ inputs.sync-name-prefix }}
         INPUT_ENV_VARS: ${{ inputs.env-vars }}