wasm demos: cyrillic recognition via PP-OCRv5

The v3 cyrillic export reads Cyrillic but drops spaces and flips case
on lookalike glyphs. Side-by-side on a rendered test line (same
preprocessing as prep_line, greedy CTC): v3 gives "еш: pаs" with glued
words, PaddlePaddle/cyrillic_PP-OCRv5_mobile_rec_onnx decodes the whole
line exactly, spaces included. Same interop contract — input
[n,3,48,W], output [n,t,852] = blank + 850 dict chars + space, matching
dict_chars' table.

The v5 dictionary only exists inside the repo's inference.yml, so a
flattened cyrillic_v5_dict.txt ships next to the demo pages.

Refs #157

Signed-off-by: artiz <artem.kustikov@gmail.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EY5KAiquN4YpVf2PXEQkVT

Author: artiz