feat(webdav): drive-aware RFC 4331 quota properties

resolve_quota only ever reported the caller's personal envelope,
ignoring the drive_id already resolved at every PROPFIND call site —
shared drives with their own quota showed the wrong numbers. Adds
AppState::resolve_webdav_quota, shared by both WebDAV surfaces:
nil drive_id or personal drive -> account envelope, shared drive ->
its own storage.drives quota/used_bytes.

Also adds quota-used-bytes/quota-available-bytes to the NextCloud-
compatible surface, which previously had no RFC 4331 support at all.

Registers webdav_quota_properties.hurl and the new
nc_webdav_quota_properties.hurl in tests/api/run.sh — neither was
wired into the suite before this change.

src/interfaces/nextcloud/report_handler.rs

@@ -211,6 +211,10 @@ async fn handle_filter_files(
                 oc_id.as_deref(),
                 &user.username,
                 &favorite_ids,
+                // REPORT results are a flat filter/search listing, not a
+                // PROPFIND on a specific collection — quota isn't
+                // meaningful here (see `AppState::resolve_webdav_quota`).
+                None,
             )
             .map_err(|e| AppError::internal_error(format!("XML write error: {}", e)))?;
         }
@@ -342,6 +346,10 @@ async fn handle_search(
                 oc_id.as_deref(),
                 &user.username,
                 &favorite_ids,
+                // REPORT results are a flat filter/search listing, not a
+                // PROPFIND on a specific collection — quota isn't
+                // meaningful here (see `AppState::resolve_webdav_quota`).
+                None,
             )
             .map_err(|e| AppError::internal_error(format!("XML write error: {}", e)))?;
         }