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>

.gitattributes

@@ -0,0 +1,8 @@
+# Normalize line endings: store LF in the repo, check out native on Windows.
+* text=auto eol=lf
+
+# Binary assets must never be line-ending converted.
+*.traineddata binary
+*.png binary
+*.jpg binary
+*.ico binary