drop the hive's push of the legacy core/meta repo

Nothing reads core/meta: builds come from internal/meta. Remove push_meta, ensure_meta_remote, meta_read_access, ensure_repo, the per-agent forge sync that only served them, and the git commit path in meta.rs; remove_permission_files now just deletes the seed files.

hive-c0re/src/paths.rs

@@ -193,13 +193,6 @@ pub fn meta_root() -> PathBuf {
     state_root().join("meta")
 }
 
-/// `meta/.git/index.lock` — git index lock; checked before meta git ops
-/// so a stale lock from a crashed process can be cleared.
-#[must_use]
-pub fn meta_git_index_lock() -> PathBuf {
-    meta_root().join(".git/index.lock")
-}
-
 /// `meta-rev/` — one file per agent naming the `internal/meta` commit its
 /// rebuild builds from (`crate::meta_rev`).
 ///