perf: round 4 — one-pass row paths, drive-selector cache, CalDAV single-parse, streamed Azure, batched hydration

Nine benchmark-gated changes (benches/ROUND4.md; every one ships with a
BEFORE/AFTER bench + equivalence gate, rollback rule as ROUND2/3):

- Row→entity path build: one-pass StoragePath::from_folder_and_name /
  from_joined + normalize_storage_name_owned + alloc-free Display —
  743→417 ns/file-row (1.78x), −5 allocs/row on every listing surface.
- WebDAV drive-selector: per-user readable_cache (single-flight, 30 s
  TTL, explicit invalidation incl. membership + group changes) replaces
  the grants join per request — 441 µs → 0.8 µs (~550x), 0 queries warm.
- CalDAV from_ical/update_ical_data: 8 full IcalParser runs per VEVENT
  → 1 (7.1x per PUT, 4.4x on 50-event imports); alloc-free split_vevents,
  chunk scan without the whole-body uppercase copy (1.4x), borrowed-key
  UID grouping (1.3x), REPORT props no longer cloned.
- PROPFIND emit: partition Vecs dropped (single-pass 404 list) + stack
  rendered RFC 3339/2822 dates, sizes, quoted etags (common::fmt,
  chrono-byte-identical, sweep-tested) on both DAV surfaces — 1.22x
  per page, 17.9→12.0 allocs/row.
- Grant-listing hydration: calendars/address books/playlists batch
  hydrate via = ANY($1) — 15 serial queries → 1 (~13x per sync poll).
- user-flags cache: get→insert → try_get_with single-flight (32→1
  queries per cold herd).
- Azure downloads: whole-blob Vec buffering → streamed SDK pages —
  TTFB 349→4 ms (87x), peak heap 480→1.9 MiB (254x) on 256 MiB blobs;
  new OXICLOUD_AZURE_ENDPOINT_URL override (Azurite/bench hook).
- Face indexing: unbounded per-image tokio::spawn → core-count
  semaphore, permit before blob read — peak heap 1175→176 MiB (6.7x).

Checks: cargo fmt, clippy --all-features --all-targets -D warnings,
cargo test --workspace (523 passed) + --features test_utils. hurl API
suite and dockerized integration DB not runnable in this environment —
left to CI.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017aJu9ghvuT8WqC31ZEGTBA

src/application/services/calendar_service.rs

@@ -189,17 +189,13 @@ impl CalendarUseCase for CalendarService {
             })
             .collect();
 
-        // Hydrate DTOs. `get_calendar` misses on trashed / deleted
-        // calendars — those are dropped from the listing rather than
-        // erroring, so a lifecycle-race doesn't turn a PROPFIND into
-        // a 5xx.
-        let mut out = Vec::with_capacity(calendar_ids.len());
-        for id in calendar_ids {
-            if let Ok(dto) = self.calendar_storage.get_calendar(&id.to_string()).await {
-                out.push(dto);
-            }
-        }
-        Ok(out)
+        // Hydrate DTOs in ONE `= ANY` round-trip (was one point SELECT
+        // per accessible calendar — K serial round-trips on every
+        // CalDAV discovery poll). Missing rows (deleted/trashed race)
+        // drop out of the result set instead of erroring, so a
+        // lifecycle-race still doesn't turn a PROPFIND into a 5xx.
+        let ids: Vec<Uuid> = calendar_ids.into_iter().collect();
+        self.calendar_storage.get_calendars_by_ids(&ids).await
     }
 
     async fn list_public_calendars(