Fix Self-Teaching language detection: parse code from dropdown label

_harvest_hf_dataset and _harvest_wikipedia received "Fula (ful)" from the
dropdown but looked it up in SUPPORTED_LANGUAGES which has "Fula / Pular —
Guinea (ful)" — no match, silently defaulted to bam. Now extract the code
from the trailing (xxx) parentheses directly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -1270,7 +1270,9 @@ def _harvest_wikipedia(lang_label: str, max_articles: int = 100) -> str:
     """Fetch Wikipedia text and append to vocabulary.jsonl."""
     if _hf_api is None:
         return "⚠️ HF_TOKEN not set."
-    lang = SUPPORTED_LANGUAGES.get(lang_label, "bam")
+    import re as _re_tmp
+    _m = _re_tmp.search(r'\((\w+)\)$', lang_label.strip())
+    lang = _m.group(1) if _m else SUPPORTED_LANGUAGES.get(lang_label, "bam")
     if lang not in ("bam", "ful"):
         return "⚠️ Supported for Bambara and Fula only."
     max_articles = int(max_articles)  # Gradio slider returns float
@@ -1304,7 +1306,10 @@ def _harvest_hf_dataset(lang_label: str, max_samples: int = 500) -> str:
     """
     if _hf_api is None:
         return "⚠️ HF_TOKEN not set."
-    lang = SUPPORTED_LANGUAGES.get(lang_label, "bam")
+    # Dropdown sends "Bambara (bam)" / "Fula (ful)" — extract the code in parens
+    import re as _re_tmp
+    _m = _re_tmp.search(r'\((\w+)\)$', lang_label.strip())
+    lang = _m.group(1) if _m else SUPPORTED_LANGUAGES.get(lang_label, "bam")
     if lang not in ("bam", "ful"):
         return "⚠️ Supported for Bambara and Fula only."
     max_samples = int(max_samples)  # Gradio slider returns float