Address review feedback: deduplicate query_type, clean unused imports, fix defaults

- Remove duplicate detect_query_type from query.py (divergent 5-type version);
  canonical 7-type version lives in query_type.py
- Fix reddit.py import to use query_type.detect_query_type
- Clean unused STOPWORDS/SYNONYMS/tokenize imports from youtube_yt, instagram,
  tiktok, scrapecreators_x, bird_x after relevance consolidation
- Fix _relevance_filter default from 0.7 to 0.0 (items without relevance
  should not silently pass the filter)
- Remove --dateafter from yt-dlp (returns 0 results for evergreen topics)
- Remove restrictSearchableAttributes from HN search (misses Ask/Show HN)
- Lower HN points filter from >5 to >2 (avoids filtering niche posts)
- Add error logging to select_openai_model HTTP failures
- Remove mise.toml and internal planning doc from repo
- Update module docstrings to describe current purpose, not migration history
- Update tests to import from canonical relevance module

scripts/lib/hackernews.py

@@ -90,13 +90,14 @@ def search_hackernews(
     core = extract_core_subject(topic)
     _log(f"Searching for '{core}' (raw: '{topic}', since {from_date}, count={count})")
 
-    # Use relevance-sorted search with minimum engagement filter
+    # Use relevance-sorted search with minimum engagement filter.
+    # NOTE: restrictSearchableAttributes=title omitted intentionally — it would
+    # miss Ask HN/Show HN threads where the topic appears in the body.
     params = {
         "query": core,
         "tags": "story",
-        "numericFilters": f"created_at_i>{from_ts},created_at_i<{to_ts},points>5",
+        "numericFilters": f"created_at_i>{from_ts},created_at_i<{to_ts},points>2",
         "hitsPerPage": str(count),
-        "restrictSearchableAttributes": "title",
     }
 
     from urllib.parse import urlencode