chore: initialize repository baseline

Import the existing Electron + React + TypeScript app as the version-control
baseline before the scanner rework (C# input/capture sidecar, resolution-anchored
layout profiles, OCR preprocessing, eval harness, rescan-merge, GOOD interop).

Housekeeping in this commit:
- Remove orphaned temp_inputhelper_block.ts (duplicate of the input-helper script).
- Ignore .claude/scheduled_tasks.lock local session state.
- Add .gitattributes to normalize line endings (LF in repo).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/features/layout/index.ts

@@ -0,0 +1,12 @@
+export { AppShell, AppMetrics, AppSidebar, AppTopbar } from "./AppLayout";
+export {
+  type AppMetricCard,
+  type AppNavigationItem,
+  type AppBarAction,
+  type NavigationId,
+  type AppSidebarProps,
+  type AppTopbarProps,
+  type AppMetricsProps,
+  type AppShellProps,
+} from "./types";
+export { appNavigationItems } from "./navigation";