Sync from GitHub main: parser fixes (SUB-TOTAL, 2-digit qty, barcode strip), ISO dates, conditional second OCR pass, non-blocking model load, OCR_SHARED_SECRET gate + 15MB cap, TIMING behind env var

perf(ocr): raise image cap to 4096px for higher quality

perf(ocr): cap image at 2048px for dual-pass speed improvement

revert(ocr): restore dual-pass and 4096px, keep timing logs

perf(ocr): increase max image size to 2048px for better accuracy

perf(ocr): halve inference time on free CPU tier

feat: initial OCR server deploy