fix(capacity): harden scope registry, scan symlink guard, and test temp dir cleanup (#2432)

Co-authored-by: heihutu <heihutu@gmail.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: houseme <4829346+houseme@users.noreply.github.com>

crates/ecstore/src/store_api/types.rs

@@ -73,6 +73,7 @@ pub struct ObjectOptions {
     pub resolved_checksum: Option<Bytes>,
     pub want_checksum: Option<Checksum>,
     pub skip_verify_bitrot: bool,
+    pub capacity_scope_token: Option<Uuid>,
 }
 
 impl ObjectOptions {