refactor(adapters): centralize curation in config/queries.json (issue #7)

- adapters/__init__.py: add load_queries() + source_config() (stdlib json,
  safe fallback to {} on missing/corrupt config so pipeline never crashes).
- config/queries.json: per-adapter blocks (hackernews.keywords, arxiv.categories,
  reddit.subreddits, rss.feeds+keywords, github.search_terms). JSON (not
  yaml) to honor Athena's dependency-free runtime; PyYAML avoided.
- hackernews: drop class AI_KEYWORDS + the DUPLICATE inline list inside
  _is_ai_relevant() (the internal drift Ty flagged). Now loads self.ai_keywords
  from config. Simplified matching to single substring pass (boundary variants
  'ai ',' ai','ai-','-ai' approximate word-boundary; dropped the niche
  'compute+tech-context' guard as not worth centralizing).
- reddit: DEFAULT_SUBREDDITS kept as fallback; __init__ prefers config.
- arxiv: DEFAULT_CATEGORIES kept as fallback; __init__ prefers config.
- rss: FEEDS + AI_KEYWORDS kept as module fallbacks; __init__ prefers config.
  Keywords stay regex form (re.search) as in original.
- github: trending queries moved to config search_terms; fallback retained.
- DELETE reddit_proof.py: standalone PoC v5 at repo root, own main()+init_db()
  + direct INSERT OR REPLACE, NOT in cron, NOT imported anywhere -> dead
  code. Also removes its byte-duplicate SUBREDDITS.

NOTE: fallback class constants remain intentionally (issue #7 cut #5: safe
rollout). Curation VALUES now live in one file; the constants are inert
unless config/queries.json is missing.

Verified: all adapters compile; config loads (HN 46 kw, RSS 10 feeds);
full dry-run fetches all 6 sources; grep confirms HN internal dup list gone.

adapters/__init__.py

@@ -1,7 +1,35 @@
 """Source adapters for AI Research Oracle."""
 
+import json
+import os
 from abc import ABC, abstractmethod
 
+# Centralized curation config (issue #7). One file, per-adapter blocks.
+# Stdlib-only (JSON, not YAML) to honor Athena's dependency-free runtime.
+_QUERIES_PATH = os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
+    "config", "queries.json")
+
+
+def load_queries():
+    """Load config/queries.json. Returns {'sources': {...}}.
+
+    Safe fallback: if the file is missing/corrupt, returns an empty
+    {'sources': {}} so adapters fall back to their class defaults
+    (constructor None-override) instead of crashing the pipeline.
+    """
+    try:
+        with open(_QUERIES_PATH) as f:
+            data = json.load(f)
+        return data if isinstance(data, dict) else {"sources": {}}
+    except Exception:
+        return {"sources": {}}
+
+
+def source_config(name: str) -> dict:
+    """Return the per-adapter block for `name`, or {} if absent."""
+    return load_queries().get("sources", {}).get(name, {}) or {}
+
 
 class SourceAdapter(ABC):
     """Base class for all ingestion adapters."""