Never block reconcile on per-file downloads; request evicted files up front

On a first attach (new Mac, reinstall) the whole tree is evicted and the
bounded per-file wait (~30s, serial) left the UI empty for hours. Reconcile
now fires all download requests immediately, sweeps the files that are
already current, and parks evicted paths as unreadable (keeping their cache
entities) — the metadata observer imports each file the moment bird
materializes it.

Workouts/Sync/SyncEngine.swift

@@ -779,12 +779,25 @@ final class SyncEngine {
         let tombstoned = await tombstones.listStubIDs()
         let dataFiles = await store.list().filter { !$0.hasPrefix("Stubs/") }
 
+        // Fire download requests for every evicted file up front so bird
+        // materializes them in parallel while this pass sweeps the current ones.
+        await store.downloadEvictedFiles(inSubdirectory: nil)
+
         var liveRoutineIDs = Set<String>()
         var liveWorkoutIDs = Set<String>()
         var liveScheduleIDs = Set<String>()
         var unreadablePaths = Set<String>()
 
         for path in dataFiles {
+            // Never block on a per-file download here: on a first attach (a new
+            // Mac, a reinstall) the whole tree is evicted and the bounded wait
+            // is ~30s per file, serially — hours of empty UI. Skip it like an
+            // unreadable path (the prune below keeps its cache entity) and let
+            // the metadata observer import it the moment it materializes.
+            if await store.isEvicted(path) {
+                unreadablePaths.insert(path)
+                continue
+            }
             let data: Data
             do {
                 data = try await store.readData(from: path)