feat: expose per-page markdown extraction to Python and Node (#53)

* feat: expose per-page markdown extraction to Python and Node (#49)

Implements the feature requested in issue #49: a list-of-pages markdown output
from the Python API. Matching the existing project pattern, the feature lives
in the Rust core and is surfaced through every binding.

- Rust core: `extract_pages_markdown` (path) and `extract_pages_markdown_mem`
  (bytes) now take `Option<&[u32]>` — `None` returns every page in document
  order; a slice restricts and preserves caller order.
- Python: new `extract_pages_markdown(path, pages=None)` and
  `extract_pages_markdown_bytes(data, pages=None)` functions plus
  `PageMarkdown` / `PagesExtractionResult` classes; stub file updated.
- Node: `extractPagesMarkdown(buffer, pages?)` — `pages` is now optional.
- Tests: 2 new Rust integration tests, 9 new Python tests, 2 new Node
  assertions. All 372 unit + 107 integration + 53 Python tests pass.

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

* chore: bump version from 1.3.0 to 1.4.0

Minor bump for the new per-page markdown extraction API exposed through
the Python and Node bindings.

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

---------

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

docs/python.md

@@ -42,6 +42,14 @@ text = pdf_inspector.extract_text("document.pdf")
 items = pdf_inspector.extract_text_with_positions("document.pdf")
 for item in items[:5]:
     print(f"'{item.text}' at ({item.x:.0f}, {item.y:.0f}) size={item.font_size}")
+
+# Per-page markdown (one Markdown string per page, plus layout metadata)
+result = pdf_inspector.extract_pages_markdown("document.pdf")
+for page in result.pages:
+    print(f"Page {page.page}: {len(page.markdown)} chars, needs_ocr={page.needs_ocr}")
+
+# Restrict to specific 0-indexed pages (preserves caller order)
+result = pdf_inspector.extract_pages_markdown("document.pdf", pages=[0, 2])
 ```
 
 ## API reference
@@ -60,6 +68,8 @@ for item in items[:5]:
 | `extract_text_with_positions_bytes(data, pages=None)` | Text with positions from bytes |
 | `extract_text_in_regions(path, page_regions)` | Extract text in bounding-box regions |
 | `extract_text_in_regions_bytes(data, page_regions)` | Region extraction from bytes |
+| `extract_pages_markdown(path, pages=None)` | Per-page Markdown + layout metadata (all pages by default) |
+| `extract_pages_markdown_bytes(data, pages=None)` | Per-page Markdown from bytes |
 
 ## Types
 
@@ -72,3 +82,7 @@ for item in items[:5]:
 **`RegionText` fields:** `text`, `needs_ocr`
 
 **`PageRegionTexts` fields:** `page` (0-indexed), `regions` (list of RegionText)
+
+**`PageMarkdown` fields:** `page` (0-indexed), `markdown`, `needs_ocr`
+
+**`PagesExtractionResult` fields:** `pages` (list of PageMarkdown), `pages_with_tables` (1-indexed), `pages_with_columns` (1-indexed), `pages_needing_ocr` (1-indexed), `is_complex`

docs/rust-api.md

@@ -79,6 +79,27 @@ let bytes = std::fs::read("document.pdf")?;
 let result = process_pdf_mem(&bytes)?;
 ```
 
+Extract per-page Markdown (one string per page, plus document-wide layout
+metadata):
+
+```rust
+use pdf_inspector::extract_pages_markdown;
+
+// Pass `None` for every page in document order, or a slice of 0-indexed
+// pages to restrict the output (caller-supplied order is preserved).
+let result = extract_pages_markdown("document.pdf", None)?;
+
+for page in &result.pages {
+    if page.needs_ocr {
+        // Route this page to OCR
+    } else {
+        println!("Page {}: {}", page.page, page.markdown);
+    }
+}
+
+println!("Complex layout? {}", result.is_complex);
+```
+
 ## Processing modes
 
 | Mode | What it does | Returns |
@@ -102,6 +123,8 @@ let result = process_pdf_mem(&bytes)?;
 | `to_markdown(text, options)` | Convert plain text to Markdown |
 | `to_markdown_from_items(items, options)` | Markdown from pre-extracted `TextItem`s |
 | `to_markdown_from_items_with_rects(items, options, rects)` | Markdown with rectangle-based table detection |
+| `extract_pages_markdown(path, pages)` | Per-page Markdown + layout metadata (file) |
+| `extract_pages_markdown_mem(bytes, pages)` | Per-page Markdown from bytes |
 
 Low-level detection functions are also available via the `detector` module (`detect_pdf_type`, `detect_pdf_type_with_config`, etc.) for callers who need `PdfTypeResult` instead of `PdfProcessResult`.
 
@@ -119,4 +142,6 @@ Low-level detection functions are also available via the `detector` module (`det
 | `LayoutComplexity` | Layout analysis: is_complex, pages_with_tables, pages_with_columns |
 | `TextItem` | Text with position, font info, and page number |
 | `MarkdownOptions` | Configuration for Markdown formatting (page numbers, etc.) |
+| `PageMarkdown` | Per-page result: page (0-indexed), markdown, needs_ocr |
+| `PagesExtractionResult` | Per-page output + 1-indexed pages_with_tables / pages_with_columns / pages_needing_ocr, is_complex |
 | `PdfError` | `Io`, `Parse`, `Encrypted`, `InvalidStructure`, `NotAPdf` |