dictprep: Russian orthographic dictionary → Scrabble noun pipeline

Build a committed Russian common-noun word list (dictprep/russian/scrabble.txt)
from the RAN orthographic dictionary, for the Эрудит ruleset.

- Stage 1 (Go, dictprep/ruwords): orfo_dict_2025.txt -> all.txt; extracts
  headwords, reconstructs "ед." singulars (suppressing plurals), pairs "и" variants.
- Stage 2 (Python brain, dictprep/ru_stage2.py): OpenCorpora (mawo-pymorphy3) +
  libmorph + orthographic notes select common nouns (nom. sing.); --trace explains
  a word's fate, --dump writes the in-memory buckets.
- libmorph C++ bridge (libmorph_check.cpp); manual_confirm.txt is merged in.
- orfo_dict_2025.txt is the committed pdftotext source of truth.
- See dictprep/README.md for methodology and reproducibility.

.gitignore

@@ -6,4 +6,13 @@
 
 # Local scratch
 /tmp/
-*.pdf
+
+# Compiled libmorph bridge (build artifact; see dictprep/README.md)
+/dictprep/libmorph_check
+
+# Stage 2 --dump debug buckets (committed: all, scrabble, manual_confirm, orfo_dict_2025)
+/dictprep/russian/undefined.txt
+/dictprep/russian/adjectives.txt
+/dictprep/russian/verbs.txt
+/dictprep/russian/singulars.txt
+/dictprep/russian/fate.tsv