Public API for pdfplumber-clj: open PDFs and extract text, words, characters,
geometric objects, and tables as plain Clojure data.

Document loading and the error model. The PDFBox parse boundary lives here;
higher namespaces work with the returned PDDocument handle.

Bounding-box math and coordinate conversion.

The public coordinate system has a top-left origin (matching Python
`pdfplumber`): a bounding box is `[x0 top x1 bottom]` in PDF user-space points
with `x0 <= x1` and `top <= bottom`. PDFBox works in a bottom-left origin, so
conversion happens here and nowhere else. All extraction code must use these
helpers rather than open-coding the arithmetic.

Page object extraction (lines, rectangles, curves, and images) via a
PDFGraphicsStreamEngine subclass.

PDFBox delivers path coordinates already transformed by the CTM into page
space (bottom-left origin); we collect painted subpaths and flip them to the
public top-left coordinate system. Only painted paths (stroked/filled) yield
objects; clip-only / no-paint paths are discarded.

Lightweight cropped page views. A view carries the document handle, a page
number, and a crop bbox; extraction functions accept it in place of a
document handle and restrict their output to the bbox. Nothing is copied or
translated — a view is just resolved into `:page`/`:bbox` options.

Table detection and extraction from ruling lines, text alignments, or
caller-supplied explicit lines. Public coordinates use
`[x0 top x1 bottom]` in a top-left origin.

Character, word, and text extraction over PDFBox's PDFTextStripper.

PDFTextStripper already reports direction-adjusted coordinates in a top-left
origin, so char maps are built directly from `getXDirAdj`/`getYDirAdj` without
a page-height flip. Words are formed by clustering chars into lines (within
`:y-tolerance`) and splitting on horizontal gaps wider than `:x-tolerance`.