fix(odm): expose store context after relocation

Expose the ECStore instance context through a narrow accessor so relocated on-demand migration backfill code no longer reaches into private storage fields.

Declare the faster-hex dependency used by the relocated native HTTP source implementation.

Co-Authored-By: heihutu <heihutu@gmail.com>

Co-Authored-By: zhi22915 <qiuzgang@gmail.com>

crates/ecstore/src/store/mod.rs

@@ -707,6 +707,10 @@ impl std::fmt::Debug for ECStore {
 /// These delegate to the process-global statics. No local state — the globals
 /// remain the single source of truth until the migration is complete.
 impl ECStore {
+    pub fn instance_ctx(&self) -> &Arc<InstanceContext> {
+        &self.ctx
+    }
+
     /// Every erasure set across all pools, pool-major order.
     ///
     /// Read-only queries that must consult each set's own copy of a