perf(storage): converge Wave 2 hot-path optimizations (#6065)

* perf(get): share inline shards and lock clients

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

* perf(ecstore): converge PUT encoding on contiguous blocks

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

* perf(get): cache codec streaming gate config

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

* fix(sse): redact projected customer headers

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

* perf(ecstore): collapse GET metadata snapshots

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

* perf(ecstore): reuse decode stripe scratch

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

* refactor(ecstore): trim decode scratch adapters

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

* test(ecstore): adapt transition checks to metadata snapshots

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

* perf(get): release metadata snapshots at ownership boundary

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

* refactor(ecstore): close cumulative fast-path findings

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

* fix(storage): preserve lock and header invariants

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

* test(ecstore): adapt cumulative paths after rebase

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

* fix(rio-v2): adapt generated metadata fixture

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

---------

Co-authored-by: heihutu <heihutu@gmail.com>

crates/ecstore/src/erasure/coding/bitrot.rs

@@ -125,6 +125,11 @@ where
         self.last_verify_duration
     }
 
+    #[cfg(test)]
+    pub(crate) fn inner_ref(&self) -> &R {
+        &self.inner
+    }
+
     /// Read a single (hash+data) block, verify hash, and copy `out.len()` bytes
     /// into `out`. Returns an error if the shard is short, the hash mismatches,
     /// or `out` is larger than one shard. On error `out`'s contents are