M2.6: shared JBIG2 globals are read once a document; Copy Image is tested on JBIG2

From CodeRabbit's review of the stack:
- Every JBIG2 image read its /JBIG2Globals afresh, within 32 MiB each but with no
  bound across an export or a redaction. A globals stream of the file, not edited since
  it was read and with its /DecodeParms direct, now has its filters undone once a
  document and is kept for the images that share it (in every clone, which share the
  file), up to 64 MiB in all. An edited one, one added in memory, or one with
  /DecodeParms by reference (another object, which can change under it) is read each
  time as before. This saves the filters only: the decoder reads the segments afresh for
  every image, so a real symbol dictionary still costs its decoding once an image.
- view.copy-image dropped "JBIG2 inside other filters" from its missing list on the
  strength of Export's test; Copy Image now has its own: a JBIG2 picture behind
  ASCIIHexDecode is found under the pointer and copied as its pixels and as a PNG, and
  one whose page information is in its globals is read through them.

A JBIG2 image's /Width and /Height are read as given directly; one by reference is an
error rather than an image of no rows.

A /JBIG2Globals reference to no object still reads as no globals: it is a reference
to null (ISO 32000-2 §7.3.10), which an entry may hold for being absent (§7.3.7), and
the renderer draws the page so. An image that needed those globals then mostly fails
to decode; in a probe of twelve pictures that decoded with them, eleven were refused
and one decoded to other pixels.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AmsdeUCdTaD72jkDw2pJKY

parity/acrobat-features.toml

@@ -130,7 +130,7 @@ milestone = "M1"
 status = "partial"
 commands = []
 tools = []
-evidence = ["crates/filters/src/ccitt.rs::decoding_gives_the_rows_back", "crates/filters/src/ccitt.rs::group_3_rows_on_bytes_read_by_the_codes_in_the_data", "crates/cos/src/document/tests.rs::fax_images_decode_with_their_parameters", "crates/filters/src/jbig2/decode.rs::both_codings_decode_to_their_samples", "crates/filters/src/jbig2/decode.rs::what_it_cannot_decode_is_an_error", "crates/cos/src/document/tests.rs::jbig2_images_decode_with_their_globals"]
+evidence = ["crates/filters/src/ccitt.rs::decoding_gives_the_rows_back", "crates/filters/src/ccitt.rs::group_3_rows_on_bytes_read_by_the_codes_in_the_data", "crates/cos/src/document/tests.rs::fax_images_decode_with_their_parameters", "crates/filters/src/jbig2/decode.rs::both_codings_decode_to_their_samples", "crates/filters/src/jbig2/decode.rs::what_it_cannot_decode_is_an_error", "crates/cos/src/document/tests.rs::jbig2_images_decode_with_their_globals", "crates/cos/src/document/tests.rs::shared_jbig2_globals_are_read_once"]
 notes = "decoded through the hayro bootstrap for display; own codecs are M1.1/M1.2. CCITT fax decoding is in filters (decode_ccitt, through hayro-ccitt), which Document::decoded_image uses for Export ▸ Images, the optimizer and redaction; so is JBIG2 decoding (decode_jbig2, through hayro-jbig2, the page bounded before it is decoded), which it uses with the image's /JBIG2Globals (within 32 MiB) for Export ▸ Images, Copy Image and redaction. Byte-aligned Group 3 is read by its end-of-line codes when the data starts with one and on bytes otherwise; still limited: data with codes but none before the first row (not as T.4 sends them) is read on bytes, as the renderer draws it, and at /K 0 may come out as other rows, which the optimizer then writes back. The bootstrap renderer draws byte-aligned Group 3 whose fill ends each end-of-line code on a byte as other rows (black box, at every /K), which decode_ccitt reads right; redaction removes Group 3 on bytes whole"
 
 [[feature]]
@@ -1598,7 +1598,7 @@ milestone = "M3"
 status = "partial"
 commands = []
 tools = []
-evidence = ["crates/ui-egui/tests/it/viewer.rs::a_clicked_picture_is_selected_and_copied_in_its_original_format", "crates/ui-egui/tests/it/viewer.rs::right_click_on_a_picture_copies_it_at_full_size", "crates/ui-egui/tests/it/viewer.rs::a_picture_inside_form_artwork_under_text_is_selected_and_copied", "crates/engine/src/tests.rs::copy_image_finds_a_picture_inside_form_artwork_under_text"]
+evidence = ["crates/ui-egui/tests/it/viewer.rs::a_clicked_picture_is_selected_and_copied_in_its_original_format", "crates/ui-egui/tests/it/viewer.rs::right_click_on_a_picture_copies_it_at_full_size", "crates/ui-egui/tests/it/viewer.rs::a_picture_inside_form_artwork_under_text_is_selected_and_copied", "crates/engine/src/tests.rs::copy_image_finds_a_picture_inside_form_artwork_under_text", "crates/engine/src/tests.rs::copy_image_copies_a_jbig2_picture_behind_another_filter", "crates/engine/src/tests.rs::copy_image_reads_the_globals_of_a_jbig2_picture"]
 notes = "Select tool: a click selects a raster image (also inside Form artwork or under text) and ⌘C copies it as a file in its original format (JPEG as stored, else PNG); right-click ▸ Copy Image copies its pixels at full resolution. Missing: inline images (BI/ID/EI), JPEG 2000 images, multi-format clipboard (file and bitmap at once), the web build"
 
 [[feature]]