Refactor: migrate pdf_parser.py to golang (#16323)

### What problem does this PR solve?

Http API based on onnx model.
pdf_parser.py to golang

### Type of change

- [x] Refactoring

internal/deepdoc/parser/pdf/compare_test.go

@@ -0,0 +1,65 @@
+//go:build manual
+
+package parser
+
+import (
+	"log/slog"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"ragflow/internal/deepdoc/parser/pdf/tools"
+)
+
+// TestBatchCompareWithPython compares Go output against Python reference
+// across 4 dimensions (text, tables, DLA, TSR raw).  It is read-only —
+// no generation, no CGO/DeepDoc dependency.  Use BATCH_SKIP_OCR=1 to
+// compare the noocr variant; PY_OCR_SUFFIX to override the Python variant.
+func TestBatchCompareWithPython(t *testing.T) {
+	level := slog.LevelInfo
+	if os.Getenv("BATCH_LOG_LEVEL") == "debug" {
+		level = slog.LevelDebug
+	}
+	if os.Getenv("BATCH_LOG_LEVEL") == "warn" {
+		level = slog.LevelWarn
+	}
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: level})))
+
+	goVariant := "ocr"
+	if os.Getenv("BATCH_SKIP_OCR") == "1" {
+		goVariant = "noocr"
+	}
+	pyVariant := os.Getenv("PY_OCR_SUFFIX")
+	if pyVariant == "" {
+		pyVariant = goVariant
+	}
+	goTextDir := filepath.Join("testdata", "output", "go", goVariant, "text")
+	pyTextDir := filepath.Join("testdata", "output", "py", pyVariant, "text")
+
+	// Read Go text files' #@meta (no aggregate JSON dependency).
+	goResults, err := tools.ReadGoTextMeta(goTextDir)
+	if err != nil || len(goResults) == 0 {
+		t.Fatalf("No Go text files in %s: %v", goTextDir, err)
+	}
+
+	// Read Python text files' #@meta
+	pyResults, err := tools.ReadPythonTextMeta(pyTextDir)
+	if err != nil || len(pyResults) == 0 {
+		t.Fatalf("No Python text files in %s: %v", pyTextDir, err)
+	}
+
+	t.Logf("Comparing %d Go × %d Python", len(goResults), len(pyResults))
+	tools.CompareWithPython(t, goResults, pyResults, goTextDir, pyTextDir)
+
+	// Compare tables.
+	goTablesDir := filepath.Join("testdata", "output", "go", goVariant, "tables")
+	pyTablesDir2 := filepath.Join("testdata", "output", "py", pyVariant, "tables")
+	tools.CompareTablesWithPython(t, goTablesDir, pyTablesDir2)
+	// Compare DLA + TSR raw intermediates.
+	goDLADir := filepath.Join("testdata", "output", "go", goVariant, "dla")
+	pyDLADir := filepath.Join("testdata", "output", "py", pyVariant, "dla")
+	tools.CompareDLAWithPython(t, goDLADir, pyDLADir)
+	goTSRRawDir := filepath.Join("testdata", "output", "go", goVariant, "tsr_raw")
+	pyTSRRawDir := filepath.Join("testdata", "output", "py", pyVariant, "tsr_raw")
+	tools.CompareTSRRawWithPython(t, goTSRRawDir, pyTSRRawDir)
+}