perf: round 20 — iCal/vCard parse allocs, owned-DTO moves, Result-collect pre-size, NC etag/favorites emit

Benchmark-gated (benches/ROUND20.md), same rule as rounds 2-19: every change
ships with a BEFORE/AFTER counting-allocator micro-benchmark and a byte-value
equivalence gate; a non-winning AFTER is rolled back (never applied). The
rollback rule is encoded in the harness (GATE FAIL exit). All 8 sections pass.

Reproduce: cargo run --release --features bench --example bench_round20_micro

- A1 CalendarEvent iCal parse: replace the throwaway per-property
  HashMap<String,Vec<String>> (DTSTART/DTEND/RECURRENCE-ID) with a direct
  VALUE=DATE scan; prop_with_params kept #[cfg(test)] (6->2 allocs/event, 4.2x)
- A2 UserDto::from: add User::into_parts and MOVE image (<=512 KiB data URI)
  + ui_preferences JSON instead of cloning on every /api/auth/me (27->14 allocs)
- A3 parse_vcard: drop the per-line to_ascii_uppercase copy + the lines Vec;
  promote ascii_ci_contains to common::text and share it (8->1 allocs/contact)
- A4 Calendar/AddressBook DTO: into_parts move incl. custom_properties map (18->10)
- I1 file-listing repos: collect::<Result<Vec>>() size-hints to 0 and grows from
  capacity 0; pre-size with Vec::with_capacity (8->1 container reallocs, 4 sites)
- I4 plaintext_stream: lazy emit iterator instead of eager Vec collect (43x wall)
- C1 NC write_etag_element: borrowed pre-escaped quote events, no owned quoted
  String/escape re-alloc; byte-identical output (3->0 allocs/PROPFIND row)
- C3 NC favorites REPORT: map.remove() move instead of get().clone() (~7 allocs/fav)

Deferred (documented in ROUND20.md): NC oc:id/trashbin buffer reuse, I1 sibling
CardDAV/CalDAV listing paths, Contact JSONB Json<Vec<_>> decode, dedup
settle_batch &str bind, and a fast DoS-resistant hasher for hot trusted-key maps
(needs a dependency decision).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JsJjcVX9RoN96DMa35Wqzd

src/interfaces/nextcloud/report_handler.rs

@@ -114,14 +114,14 @@ async fn handle_filter_files(
         }
     }
 
-    let file_map: HashMap<String, FileDto> = file_service
+    let mut file_map: HashMap<String, FileDto> = file_service
         .get_files_by_ids(&file_ids)
         .await
         .map_err(|e| AppError::internal_error(format!("Failed to resolve favorite files: {e}")))?
         .into_iter()
         .map(|f| (f.id.clone(), f))
         .collect();
-    let folder_map: HashMap<String, FolderDto> = folder_service
+    let mut folder_map: HashMap<String, FolderDto> = folder_service
         .get_folders_by_ids(&folder_ids)
         .await
         .map_err(|e| AppError::internal_error(format!("Failed to resolve favorite folders: {e}")))?
@@ -131,16 +131,21 @@ async fn handle_filter_files(
 
     let mut files: Vec<FileDto> = Vec::new();
     let mut folders: Vec<FolderDto> = Vec::new();
+    // Move the DTO out of the map instead of cloning it: the maps are built
+    // just above solely to hydrate `files`/`folders` in favorites order and are
+    // dropped at fn end, so the clone was pure waste. `favorites.item_id` is
+    // unique per user, so `remove` drops nothing needed and the favorites order
+    // is preserved (benches/ROUND20.md §C3).
     for fav in &favorites {
         match fav.item_type.as_str() {
             "file" => {
-                if let Some(f) = file_map.get(&fav.item_id) {
-                    files.push(f.clone());
+                if let Some(f) = file_map.remove(&fav.item_id) {
+                    files.push(f);
                 }
             }
             "folder" => {
-                if let Some(f) = folder_map.get(&fav.item_id) {
-                    folders.push(f.clone());
+                if let Some(f) = folder_map.remove(&fav.item_id) {
+                    folders.push(f);
                 }
             }
             _ => {}