feat: v2.8 — Instagram Reels source + TikTok ScrapeCreators migration

Add Instagram Reels as the 8th research source via ScrapeCreators API.
One API key (SCRAPECREATORS_API_KEY) now covers both TikTok and Instagram.

- Add scripts/lib/instagram.py: keyword search, transcript extraction,
  relevance scoring, engagement metrics (views, likes, comments)
- Add InstagramItem to schema, normalization, scoring, dedup, rendering
- Add Instagram to orchestrator pipeline, watchlist, and UI spinners
- Update SKILL.md: stats template, citation priority, item format,
  URL-to-name extraction rules, anti-Sources instruction
- Update README and CHANGELOG for v2.8
- Fix: Instagram/TikTok not running in --search= web-only path
- Fix: web stats line showing full URLs instead of domain names
- Replace APIFY_API_TOKEN with SCRAPECREATORS_API_KEY throughout

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

scripts/lib/dedupe.py

@@ -46,7 +46,7 @@ def jaccard_similarity(set1: Set[str], set2: Set[str]) -> float:
 
 
 AnyItem = Union[schema.RedditItem, schema.XItem, schema.YouTubeItem, schema.TikTokItem,
-                schema.HackerNewsItem, schema.PolymarketItem, schema.WebSearchItem]
+                schema.InstagramItem, schema.HackerNewsItem, schema.PolymarketItem, schema.WebSearchItem]
 
 
 def get_item_text(item: AnyItem) -> str:
@@ -59,6 +59,8 @@ def get_item_text(item: AnyItem) -> str:
         return f"{item.title} {item.channel_name}"
     elif isinstance(item, schema.TikTokItem):
         return f"{item.text} {item.author_name}"
+    elif isinstance(item, schema.InstagramItem):
+        return f"{item.text} {item.author_name}"
     elif isinstance(item, schema.PolymarketItem):
         return f"{item.title} {item.question}"
     elif isinstance(item, schema.WebSearchItem):
@@ -78,6 +80,8 @@ def _get_cross_source_text(item: AnyItem) -> str:
         return item.text[:100]
     if isinstance(item, schema.TikTokItem):
         return item.text[:100]
+    if isinstance(item, schema.InstagramItem):
+        return item.text[:100]
     if isinstance(item, schema.HackerNewsItem):
         title = item.title
         if title.startswith("Show HN:"):
@@ -206,6 +210,14 @@ def dedupe_tiktok(
     return dedupe_items(items, threshold)
 
 
+def dedupe_instagram(
+    items: List[schema.InstagramItem],
+    threshold: float = 0.7,
+) -> List[schema.InstagramItem]:
+    """Dedupe Instagram items."""
+    return dedupe_items(items, threshold)
+
+
 def dedupe_hackernews(
     items: List[schema.HackerNewsItem],
     threshold: float = 0.7,