feat(dedup): CDC sub-file deduplication with FastCDC + parallel chunk storage + dedup skip

- Replace whole-file SHA-256 dedup with FastCDC 2020 content-defined chunking
  (min 64KB, avg 256KB, max 1MB) + BLAKE3 hashing
- Add chunk_manifests table (file_hash → chunk_hashes[] + chunk_sizes[])
- Add put_blob_from_bytes to BlobStorageBackend trait (all 7 backends)
- 3-phase store_chunks pipeline:
  Phase 0: batch-check existing chunks (single PG query)
  Phase 1: selective disk read (skip existing chunks entirely)
  Phase 2: parallel upload with buffer_unordered(8)
- CDC-aware read_blob_stream and read_blob_range_stream with legacy fallback
- Transactional manifest + chunk ref-count cascade on remove_reference
- 12 CDC tests (determinism, reassembly, contiguity, sub-file dedup, etc.)
- Update deduplication.md to reflect new architecture

src/infrastructure/services/retry_blob_backend.rs

@@ -14,6 +14,7 @@ use crate::application::ports::blob_storage_ports::{
     BlobStorageBackend, BlobStream, StorageHealthStatus,
 };
 use crate::domain::errors::DomainError;
+use bytes::Bytes;
 
 // ── Retry policy ───────────────────────────────────────────────────
 
@@ -139,6 +140,25 @@ impl BlobStorageBackend for RetryBlobBackend {
         })
     }
 
+    fn put_blob_from_bytes(
+        &self,
+        hash: &str,
+        data: Bytes,
+    ) -> Pin<Box<dyn std::future::Future<Output = Result<u64, DomainError>> + Send + '_>> {
+        let inner = self.inner.clone();
+        let policy = self.policy.clone();
+        let hash = hash.to_string();
+        Box::pin(async move {
+            retry_async(&policy, &format!("put_blob_from_bytes({hash})"), || {
+                let inner = inner.clone();
+                let hash = hash.clone();
+                let data = data.clone();
+                async move { inner.put_blob_from_bytes(&hash, data).await }
+            })
+            .await
+        })
+    }
+
     fn get_blob_stream(
         &self,
         hash: &str,