extract_tables: try vector-grid detectors before text heuristic (#85)

* extract_tables: try vector-grid detectors before text heuristic

extract_tables_in_regions_mem previously ran only the text-only
heuristic detector (tables::detect_tables) on the items inside each
region, discarding the rects and lines that extract_page_text_items
returned. That left the rect-backed and line-backed detectors
(detect_tables_from_rects, detect_tables_from_lines) unused by the
public region-scoped extraction path — they only ran through
detect_vector_grid_in_region_mem, which most callers don't use.

Keep the rects and lines, filter them to each region, and try in
order: rect detector → line detector → heuristic. Each candidate's
markdown is quality-gated by the existing needs_ocr checks
(is_garbage_text, is_cid_garbage, detect_encoding_issues,
looks_like_partial_table_ex); only the first clean output wins.
If all three produce empty or noisy output we still return
needs_ocr=true, matching prior behavior.

Effect on real prod-shape inputs from shadow logs:

  Full-page ruled ledger, 6 cols x ~15 rows:
    before: heuristic emits a 355-char two-row fragment
    after:  line detector emits the full 6520-char table

  Multi-row key/value layout with paragraph values:
    before: heuristic emits a 188-char header-only fragment
    after:  rect detector emits the full 1733-char table including
            the multi-bullet description cell

Existing fixtures that already passed via the heuristic continue to
pass: the quality gate rejects partial vector-grid output and falls
through, so the heuristic still wins where it produced the cleaner
result.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Bump version from 1.8.9 to 1.8.10

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/integration_tests.rs

@@ -1648,6 +1648,33 @@ fn test_bits_pilani_page8_table_detection() {
     assert!(!region.needs_ocr, "Page 8 table should still be detected");
 }
 
+#[test]
+fn test_extract_tables_in_regions_uses_line_grid() {
+    // Stroked-grid table (m/l/S path operators forming a 2x2 grid).
+    // The heuristic text-only detector handles the same cells already,
+    // so this guards that the line-backed path doesn't regress: the
+    // markdown still contains all four data cells.
+    let buf = synthetic_vector_grid_pdf(false);
+    let results =
+        extract_tables_in_regions_mem(&buf, &[(0, vec![[40.0, 50.0, 220.0, 760.0]])]).unwrap();
+    let region = &results[0].regions[0];
+    assert!(
+        !region.needs_ocr,
+        "stroked-grid table should be extracted, got needs_ocr=true"
+    );
+    for tok in ["A1", "B1", "A2", "B2"] {
+        assert!(
+            region.text.contains(tok),
+            "expected '{tok}' in output, got: {}",
+            region.text
+        );
+    }
+    assert!(
+        region.text.contains('|'),
+        "expected pipe-delimited markdown"
+    );
+}
+
 // =========================================================================
 // extract_tables_with_structure_mem tests (TSR-aware path)
 // =========================================================================