perf: round 9 — decorator PUT reactivation, session/search/dedup alloc purges, PROPFIND join!, folder-level cascade

Benchmark-gated round (benches/ROUND9.md): every change carries a
BEFORE/AFTER bench with equivalence/safety gates; verdicts below are from
the committed harnesses on 4 cores / local PG 16.

Backend:
- Blob decorators (Retry/Cached) now forward put_blob_from_bytes_unsynced
  + sync_blobs — the trait default had silently reinstated HEAD-before-PUT
  per chunk on decorated remote stacks, undoing ROUND3 §8. Full production
  stack: 500 probes -> 0, 1.9x wall at 10 ms RTT (bench_s3_put §3).
- NC PROPFIND per-page enrichment triple (favorites / oc:fileid / dead
  props) overlapped with tokio::join!: 2.07x local, 2.86x at 5 ms RTT
  (bench_nc_enrich_join, injected-latency decide-by-bench).
- Search enrichment consumes its DTOs and carries the interned Arc<str>
  display fields end-to-end (SearchFileResultDto type change, OpenAPI
  shape preserved): enrich_file 2.0x, 11.6 -> 2.2 allocs/row; the NC
  REPORT conversion stops re-running all three classifiers per row
  (bench_search_enrich).
- NC session Arc end-to-end: SharedNcSession extractor (8 -> 0 allocs),
  Arc<FolderDto> chroot cache (4 -> 0/hit), single shared Arc<CurrentUser>
  + lazy span render (11 -> 6/build) (bench_nc_session).
- Storage micro-pack: atomic create_new chunk writes (2.1x fresh),
  stream_chunks over the manifest Arc (4097 -> 0 allocs/read incl. the
  Range path), manifest single-flight (herd 64 -> 1 loads), hex_lower for
  chunk Content-MD5 (18 -> 1 allocs) (bench_storage_micro).
- OCS capabilities memoized into OnceLock<[Bytes;2]>: 237x, 102 -> 0
  allocs/poll, byte-identical (bench_capabilities_static).
- Drive::is_empty COUNT(*) sum -> EXISTS: 34.4x on a 100k-file drive
  (bench_drive_is_empty).
- favorites/recents row-map ROUND7 port: path/name/blob_hash moved,
  -2.75 allocs/row (bench_resource_row_map §2).
- Folder rows decode binary UUIDs (ROUND6 §10 port): 1.03-1.07x page
  fetch, honest verdict incl. one noise-band wash documented
  (bench_folder_uuid_decode).
- Authz: file cascade decision decomposed into memoized folder-level
  decision + direct-grant lookup (ROUND8 deferred item). Cold shared-album
  first view 592 -> 418 µs/thumb; warm path unchanged; safety gates incl.
  new direct-grant sibling isolation, revoke-flush re-verified, full
  integration authz suite green (bench_thumbnail_cascade_cache).

Frontend (vitest gates committed beside the code):
- resolveLabel/resolveRecipient O(directory) scan -> id-keyed Map: 13.9x
  (recipients.bench.test.ts).
- ResourceList selection-prune effect skips when nothing is selected
  (100 -> 0 Set builds per drain) and the photos timeline reads a
  listener-fed mobile flag instead of matchMedia per recompute
  (listDerives.bench.test.ts).

Verification: cargo fmt + clippy --all-features --all-targets -D warnings
clean; 524 unit + 554 integration (--cfg integration_tests) tests pass;
frontend npm run check clean with 293 vitest tests green.

Deferred with rationale in ROUND9.md: CalDAV authz-before-fetch reorder
(maintainer sign-off), per-page batched parent resolution, JWT-claims
Arc<str>, batch_operations signature widening.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XDc9VtXvskJ6dnMRraSndn

src/application/dtos/search_dto.rs

@@ -1,4 +1,5 @@
 use serde::{Deserialize, Serialize};
+use std::sync::Arc;
 use utoipa::ToSchema;
 
 /**
@@ -109,8 +110,10 @@ pub struct SearchFileResultDto {
     pub path: String,
     /// Size in bytes
     pub size: u64,
-    /// MIME type
-    pub mime_type: String,
+    /// MIME type — `Arc<str>` so enrichment reuses `FileDto`'s interned
+    /// value (an atomic increment) instead of allocating per result row.
+    #[schema(value_type = String)]
+    pub mime_type: Arc<str>,
     /// Parent folder ID
     pub folder_id: Option<String>,
     /// Creation timestamp
@@ -122,11 +125,14 @@ pub struct SearchFileResultDto {
     /// Human-readable file size (e.g., "2.5 MB")
     pub size_formatted: String,
     /// CSS icon class for the file type (e.g., "fas fa-file-pdf")
-    pub icon_class: String,
+    #[schema(value_type = String)]
+    pub icon_class: Arc<str>,
     /// Extra CSS class for icon styling (e.g., "pdf-icon", "code-icon js-icon")
-    pub icon_special_class: String,
+    #[schema(value_type = String)]
+    pub icon_special_class: Arc<str>,
     /// Content category: "document", "image", "video", "audio", "archive", "code", "other"
-    pub category: String,
+    #[schema(value_type = String)]
+    pub category: Arc<str>,
     /// Raw BLAKE3 content hash. Feeds `FileDto::content_hash` and
     /// `File::compute_etag` when search results are converted to
     /// `FileDto` (NC REPORT/SEARCH response). Defaults to `String::new()`
@@ -267,9 +273,11 @@ pub struct SearchSuggestionItem {
     /// Path for context
     pub path: String,
     /// CSS icon class
-    pub icon_class: String,
+    #[schema(value_type = String)]
+    pub icon_class: Arc<str>,
     /// Extra CSS class for icon styling
-    pub icon_special_class: String,
+    #[schema(value_type = String)]
+    pub icon_special_class: Arc<str>,
     /// Relevance score
     pub relevance_score: u32,
 }