feat(dict): build the corpus and word meanings from the Wikimedia viwiktionary dump

reader for both wikitext dialects; `meanings(word, ord, pos, gloss)` table; `meaning_count`/`words_with_meaning`/`source_pages` in meta, `source_rows` gone, builder_version 5; `--dump`/`--min-pages` replace `--kaikki`; attribution names the dump and the definition excerpts; 36,200 words, 96.9% with a meaning, every kaikki word kept.

.github/workflows/ci.yml

@@ -137,9 +137,10 @@ jobs:
             grep -qx "$required" files.txt || { echo "missing from the image: $required"; exit 1; }
           done
 
-          # The upstream export must never reach the final image.
-          if grep -q '\.jsonl$' files.txt; then
-            echo "the upstream wordlist leaked into the image"
+          # The upstream dump, compressed or not, must never reach the final
+          # image.
+          if grep -Eq '\.(bz2|xml)$' files.txt; then
+            echo "the upstream dump leaked into the image"
             exit 1
           fi