feat: enrich script working, redesigning to sub-stage architecture

- Enrich script functional with timeout, progress tracking, rejection mechanism
- Identified ordering issue: CEFR voting needs validated translations first
- Redesign: round1_gloss → round1_example → round1_translations → round1_cefr
- Update data-pipeline.md with new sub-stage design and roadmap
- Qwen3.5-4B confirmed working with thinking disabled

data-pipeline/db/schema.sql

@@ -60,6 +60,13 @@ CREATE TABLE IF NOT EXISTS model_translation_cefr_votes (
   UNIQUE (translation_id, model_name)
 );
 
+CREATE TABLE IF NOT EXISTS model_translation_rejections (
+  id             INTEGER PRIMARY KEY,
+  translation_id INTEGER NOT NULL REFERENCES translations(id),
+  model_name     TEXT    NOT NULL,
+  UNIQUE (translation_id, model_name)
+);
+
 CREATE TABLE IF NOT EXISTS generated_glosses (
   id         INTEGER PRIMARY KEY,
   entry_id   INTEGER NOT NULL REFERENCES entries(id),