feat(extractor): geometric underline detection on TextItem (#116)

* feat(extractor): geometric underline detection on TextItem (ENG-5015)

PDFs carry no underline font flag — underlines are stroked horizontal
lines or thin filled rects drawn under the baseline. Correlate those
graphics (already parsed from the content stream) with text items in a
post-pass: a rule within ~0.35em below the baseline covering >=60% of
an item's width marks is_underline.

Exposed through the napi and python bindings. Verified on real docs:
4/4 underlined sentences flagged on a Japanese report, links/headings
flagged on 8 of 10 underline-bearing eval docs, zero flags on docs
without underlines. Known FP source (table cell borders) documented —
downstream applies inline styling only to plain-text regions.

napi 1.9.8 -> 1.9.9.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(extractor): underline rules only from painted rects, normalized extents (review)

Two review fixes: (1) normalize rect extents before the thickness/width
checks — `re` operands pass through the CTM so width/height can be
negative, which missed negative-width rules and let negative-height
bands pass as thin; (2) only feed painted rects to underline detection —
`re` rects now wait in a pending list until a paint operator (S/s, f/F/
f*, B/B*/b/b*) confirms them, and `re W n` clip-only paths are discarded
at `n`, so invisible clip boundaries no longer underline nearby text.
Marking moved into content_stream where paint state lives (pre-rotation,
consistent device space).

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(extractor): harden underline detection

* feat(cli): export positioned text item json

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

napi/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@firecrawl/pdf-inspector",
-  "version": "1.9.8",
+  "version": "1.9.9",
   "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",

napi/src/lib.rs

@@ -80,6 +80,9 @@ pub struct TextItem {
     pub page: u32,
     pub is_bold: bool,
     pub is_italic: bool,
+    /// Underline detected geometrically (drawn rule/thin rect under the
+    /// baseline) — PDFs carry no underline font flag.
+    pub is_underline: bool,
     pub item_type: ItemType,
     /// URL for link items, `None` for other types.
     pub link_url: Option<String>,
@@ -290,6 +293,7 @@ pub fn extract_text_with_positions(
                     page: item.page,
                     is_bold: item.is_bold,
                     is_italic: item.is_italic,
+                    is_underline: item.is_underline,
                     item_type,
                     link_url,
                 }