refactor(modules): drop dead group_collection_repo::list_for_owner (§11.6 review)

The single-kind `list_for_owner` was superseded by `list_all_for_owner`
(the apply diff and `collection_report` both moved to it during the docs
slice). It had no callers but, being `pub`, escaped the dead-code lint —
removing it drops two unexercised SQL queries.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/manager-core/src/group_collection_repo.rs

@@ -18,39 +18,6 @@ use sqlx::{PgPool, Postgres, Transaction};
 
 use crate::config_resolver::CHAIN_LEVELS_CTE;
 
-/// List the collection names of `kind` declared **directly at** `owner` (not
-/// inherited), case-insensitively sorted. Used by `load_current` (apply diff)
-/// and the read-only `collections ls`.
-pub async fn list_for_owner(
-    pool: &PgPool,
-    owner: ScriptOwner,
-    kind: &str,
-) -> Result<Vec<String>, sqlx::Error> {
-    let rows: Vec<(String,)> = match owner {
-        ScriptOwner::App(a) => {
-            sqlx::query_as(
-                "SELECT name FROM group_collections \
-                 WHERE app_id = $1 AND kind = $2 ORDER BY LOWER(name)",
-            )
-            .bind(a.into_inner())
-            .bind(kind)
-            .fetch_all(pool)
-            .await?
-        }
-        ScriptOwner::Group(g) => {
-            sqlx::query_as(
-                "SELECT name FROM group_collections \
-                 WHERE group_id = $1 AND kind = $2 ORDER BY LOWER(name)",
-            )
-            .bind(g.into_inner())
-            .bind(kind)
-            .fetch_all(pool)
-            .await?
-        }
-    };
-    Ok(rows.into_iter().map(|(n,)| n).collect())
-}
-
 /// List **all** shared-collection declarations at `owner` as `(name, kind)`
 /// pairs, sorted. Used by the kind-aware apply diff and `collections ls`.
 pub async fn list_all_for_owner(