Add schedule-image OCR workflow and standalone Windows packaging

[sun33sun]

What changed

• Add a complete WinForms workflow for selecting exactly four schedule images, running OCR, merging records by date, reviewing validation issues, editing results, and exporting the six required columns to XLSX.
• Add reusable schedule extraction, calendar validation, duplicate/missing-workday handling, and dependency-free OOXML export projects.
• Add 46 schedule and Excel tests, plus OCR native-resource lifecycle fixes.
• Embed the three PP-OCRv5 ONNX models and dictionary in the application and add a reproducible Windows x64 self-contained single-file publish profile.
• Add a headless --self-test that verifies embedded-model extraction, ONNX Runtime, OpenCV, and OCR inference.

Why

This implements the local four-image schedule consolidation requirements documented in 需求.md, including explicit handling for missing dates, duplicates, invalid weekdays, empty roles, ambiguous columns, and cross-month data.

User impact

Users can process the full workflow offline, inspect and correct OCR output before export, and distribute a single Windows x64 EXE without requiring .NET, Python, CUDA, Office, or an external models directory.

Generated dist/ binaries are intentionally excluded from source control.

Validation

• dotnet build RapidOCRCSharp.sln -c Release --no-restore — passed with 0 warnings and 0 errors
• RapidOCRLib.Tests — 1/1 passed
• RapidOCRSchedule.Tests — 46/46 passed
• Standalone EXE copied to a clean directory outside the repository — --self-test exited 0, all four embedded model files were materialized, and the normal GUI startup remained responsive