fix(fuse): read the size again for a baseline row without a revision id

A mirror upload that Drive did not list yet when it was read back left a
baseline row with no revision id. The next walk reused the recorded size
whenever the modification time matched, and a row without an id never
counts as moved. So a revision another computer saved in the same second
looked unchanged and never arrived (B254). The B250 simulation hit this
about one run in five on CI.

A row without an id now reuses its size only while Drive gives no id
either. Otherwise the walk reads the size, and an unchanged file gets
Drive's revision id written into its row, so each row costs one extra
read. Rows from before schema 44 are read once after upgrading.

crates/pdfs-fuse/src/sync.rs

@@ -776,7 +776,23 @@ impl Core {
             }
 
             match plan_file(l, r, baseline.get(rel)) {
-                FilePlan::Unchanged => {}
+                // The size was read for real for a row without a revision id
+                // (B254), and still matches: give the row the id, so later
+                // walks trust the recorded size again.
+                FilePlan::Unchanged => {
+                    if let (Some(base), Some(revision)) =
+                        (baseline.get(rel), r.and_then(|r| r.revision.as_ref()))
+                        && base.remote_revision_id.is_none()
+                    {
+                        let row = StoredSyncEntry {
+                            remote_revision_id: Some(revision.clone()),
+                            ..base.clone()
+                        };
+                        if let Err(e) = self.db.sync_entry_upsert(folder_id, &row) {
+                            debug!(rel, error = ?e, "sync: cannot record the revision id");
+                        }
+                    }
+                }
                 FilePlan::AdoptBaseline => {
                     // First sync of a file the same size on both sides: the apply
                     // step hashes the local copy and records the baseline only if