modularize app and database internals

- Extract editor, form, export, and schema modules
- Add database workflow integration tests

tests/database_workflows.rs

@@ -0,0 +1,70 @@
+use rogue_agenda::{
+    Database,
+    model::{ItemChanges, ViewKind},
+};
+use tempfile::tempdir;
+
+fn all_items(database: &Database) -> rogue_agenda::model::ViewDef {
+    database
+        .views()
+        .unwrap()
+        .into_iter()
+        .find(|view| view.kind == ViewKind::List)
+        .unwrap()
+}
+
+#[test]
+fn completing_a_recurring_item_preserves_wall_time() {
+    let directory = tempdir().unwrap();
+    let path = directory.path().join("recurring.agnd");
+    let mut database = Database::open(&path).unwrap();
+    let item = database.add_item("Weekly review").unwrap();
+    database
+        .update_item(
+            item,
+            &ItemChanges {
+                when_at: Some(Some("2026-09-01T14:30:00+00:00".into())),
+                recurrence: Some("weekly".into()),
+                ..ItemChanges::default()
+            },
+        )
+        .unwrap();
+
+    database.toggle_done(&[item]).unwrap();
+
+    let items = database.items(&all_items(&database), "").unwrap();
+    let next = items.iter().find(|candidate| candidate.id != item).unwrap();
+    assert!(
+        next.when_at
+            .as_deref()
+            .unwrap()
+            .contains("2026-09-08T14:30:00")
+    );
+}
+
+#[test]
+fn completed_recurring_ical_roundtrip_does_not_create_a_duplicate() {
+    let directory = tempdir().unwrap();
+    let source_path = directory.path().join("source.agnd");
+    let mut source = Database::open(&source_path).unwrap();
+    let item = source.add_item("Prepare launch").unwrap();
+    source
+        .update_item(
+            item,
+            &ItemChanges {
+                when_at: Some(Some("2026-09-01T14:30:00+00:00".into())),
+                recurrence: Some("every 2 weeks".into()),
+                ..ItemChanges::default()
+            },
+        )
+        .unwrap();
+    source.toggle_done(&[item]).unwrap();
+
+    let export_path = directory.path().join("tasks.ics");
+    source.export("ics", &export_path, None).unwrap();
+
+    let target_path = directory.path().join("target.agnd");
+    let mut target = Database::open(&target_path).unwrap();
+    assert_eq!(target.import_path(&export_path).unwrap(), 2);
+    assert_eq!(target.items(&all_items(&target), "").unwrap().len(), 2);
+}