v0.3.2 - robust per-page detection + list-box fix

Patch release: robustness and a list-box fix, both found by real-world testing.

Detection degrades gracefully (the headline fix)

detect() / make_fillable() used to refuse the entire document on the first image-only page. Now an image-only or error-throwing page is skipped with a warning and the rest of the document is processed. ScannedPDFError is raised only when every page is image-only. A mostly-vector form with one scanned page now yields the fields from its vector pages instead of nothing.

Other robustness fixes

• fill() with a list value on a non-multi-select field now raises a clear error instead of a cryptic dependency crash.
• read_fields() skips a single malformed widget (with a warning) instead of aborting, and guards against a circular /Parent chain that could hang.
• flatten() is a no-op on a PDF with no fields instead of raising.

Also (from 0.3.1, rolled in)

• Building a list box with a rect too short to fit one option row no longer crashes; it raises a clear error.

Install: pip install acroforge==0.3.2