fix: simplify region text extraction to trust layout model ordering

When fire-pdf sends pre-segmented bboxes from the layout model,
pdf-inspector no longer runs column detection, stream-order heuristics,
or newspaper/tabular mode detection within the region. These heuristics
conflict with the layout model's decisions and cause wrong reading order.

Region extraction now simply: Y-sorts items, groups into lines, and
sorts within each line by X position. The heavy heuristics remain
available for standalone full-page extraction.

Eval showed pure OCR (0.2875 NED) beating native+heuristics (0.2916)
across all categories, especially multi-column (-0.08) and newspaper
(-0.16). This change should close that gap.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

napi/package.json

@@ -1,6 +1,6 @@
 {
   "name": "firecrawl-pdf-inspector",
-  "version": "0.3.3",
+  "version": "0.3.4",
   "description": "Fast PDF classification and text extraction. Detect text-based vs scanned PDFs, extract text by region with quality checks. Native Rust performance via napi-rs.",
   "main": "index.js",
   "types": "index.d.ts",