DRY pass #2, batch 8: the Rust and ffi docs (#5372)

sync/mod.rs listed 5 of its 9 modules; migrate's doc sat above the v9 SQL;
client.rs had items after its test module; the ffi's sync_now doc had fused
into client_update's; complete_reminder (ffi and EditorAction) still said
recurrence advancement was to come, though the core does it; NoteQuery.view
listed views the core never matched and claimed it validated. Test scratch
dirs drop the old ts-/iw- prefixes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

desktop/src-tauri/src/crossover.rs

@@ -90,7 +90,8 @@ mod tests {
     fn root() -> (PathBuf, PathBuf) {
         static SEQ: AtomicU32 = AtomicU32::new(0);
         let n = SEQ.fetch_add(1, Ordering::Relaxed);
-        let root = std::env::temp_dir().join(format!("iw-crossover-{}-{n}", std::process::id()));
+        let root =
+            std::env::temp_dir().join(format!("inkwell-crossover-{}-{n}", std::process::id()));
         (root.join("old"), root.join("new"))
     }