feat: Add WebSearch as third source with zero-config fallback

Add Claude's built-in WebSearch tool as a third research source for
/last30days. This enables the skill to work out of the box with zero
API keys while preserving Reddit/X as the primary sources.

Key changes:
- Add WebSearchItem schema for web results (no engagement metrics)
- Add score_websearch_items() with 55/45 relevance/recency weighting
- Apply -15pt source penalty so WebSearch ranks below Reddit/X
- Add --include-web CLI flag to opt-in to WebSearch
- Return 'web' mode when no API keys configured (zero-config)
- Update render.py with [WEB] source label formatting

When WebSearch is enabled, the script outputs instructions for Claude
to use its built-in WebSearch tool, then synthesize results together.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/lib/websearch.py

@@ -0,0 +1,195 @@
+"""WebSearch module for last30days skill.
+
+NOTE: WebSearch uses Claude's built-in WebSearch tool, which runs INSIDE Claude Code.
+Unlike Reddit/X which use external APIs, WebSearch results are obtained by Claude
+directly and passed to this module for normalization and scoring.
+
+The typical flow is:
+1. Claude invokes WebSearch tool with the topic
+2. Claude passes results to parse_websearch_results()
+3. Results are normalized into WebSearchItem objects
+"""
+
+import re
+from typing import Any, Dict, List, Optional
+from urllib.parse import urlparse
+
+from . import schema
+
+
+# Domains to exclude (Reddit and X are handled separately)
+EXCLUDED_DOMAINS = {
+    "reddit.com",
+    "www.reddit.com",
+    "old.reddit.com",
+    "twitter.com",
+    "www.twitter.com",
+    "x.com",
+    "www.x.com",
+    "mobile.twitter.com",
+}
+
+
+def extract_domain(url: str) -> str:
+    """Extract the domain from a URL.
+
+    Args:
+        url: Full URL
+
+    Returns:
+        Domain string (e.g., "medium.com")
+    """
+    try:
+        parsed = urlparse(url)
+        domain = parsed.netloc.lower()
+        # Remove www. prefix for cleaner display
+        if domain.startswith("www."):
+            domain = domain[4:]
+        return domain
+    except Exception:
+        return ""
+
+
+def is_excluded_domain(url: str) -> bool:
+    """Check if URL is from an excluded domain (Reddit/X).
+
+    Args:
+        url: URL to check
+
+    Returns:
+        True if URL should be excluded
+    """
+    try:
+        parsed = urlparse(url)
+        domain = parsed.netloc.lower()
+        return domain in EXCLUDED_DOMAINS
+    except Exception:
+        return False
+
+
+def parse_websearch_results(
+    results: List[Dict[str, Any]],
+    topic: str,
+) -> List[Dict[str, Any]]:
+    """Parse WebSearch results into normalized format.
+
+    This function expects results from Claude's WebSearch tool.
+    Each result should have: title, url, snippet, and optionally date/relevance.
+
+    Args:
+        results: List of WebSearch result dicts
+        topic: Original search topic (for context)
+
+    Returns:
+        List of normalized item dicts ready for WebSearchItem creation
+    """
+    items = []
+
+    for i, result in enumerate(results):
+        if not isinstance(result, dict):
+            continue
+
+        url = result.get("url", "")
+        if not url:
+            continue
+
+        # Skip Reddit/X URLs (handled separately)
+        if is_excluded_domain(url):
+            continue
+
+        title = str(result.get("title", "")).strip()
+        snippet = str(result.get("snippet", result.get("description", ""))).strip()
+
+        if not title and not snippet:
+            continue
+
+        # Parse date if provided
+        date = result.get("date")
+        date_confidence = "low"
+        if date:
+            # Validate date format
+            if re.match(r'^\d{4}-\d{2}-\d{2}$', str(date)):
+                date_confidence = "med"  # WebSearch dates are often approximate
+            else:
+                date = None
+
+        # Get relevance if provided, default to 0.5
+        relevance = result.get("relevance", 0.5)
+        try:
+            relevance = min(1.0, max(0.0, float(relevance)))
+        except (TypeError, ValueError):
+            relevance = 0.5
+
+        item = {
+            "id": f"W{i+1}",
+            "title": title[:200],  # Truncate long titles
+            "url": url,
+            "source_domain": extract_domain(url),
+            "snippet": snippet[:500],  # Truncate long snippets
+            "date": date,
+            "date_confidence": date_confidence,
+            "relevance": relevance,
+            "why_relevant": str(result.get("why_relevant", "")).strip(),
+        }
+
+        items.append(item)
+
+    return items
+
+
+def normalize_websearch_items(
+    items: List[Dict[str, Any]],
+    from_date: str,
+    to_date: str,
+) -> List[schema.WebSearchItem]:
+    """Convert parsed dicts to WebSearchItem objects.
+
+    Args:
+        items: List of parsed item dicts
+        from_date: Start of date range (YYYY-MM-DD)
+        to_date: End of date range (YYYY-MM-DD)
+
+    Returns:
+        List of WebSearchItem objects
+    """
+    result = []
+
+    for item in items:
+        web_item = schema.WebSearchItem(
+            id=item["id"],
+            title=item["title"],
+            url=item["url"],
+            source_domain=item["source_domain"],
+            snippet=item["snippet"],
+            date=item.get("date"),
+            date_confidence=item.get("date_confidence", "low"),
+            relevance=item.get("relevance", 0.5),
+            why_relevant=item.get("why_relevant", ""),
+        )
+        result.append(web_item)
+
+    return result
+
+
+def dedupe_websearch(items: List[schema.WebSearchItem]) -> List[schema.WebSearchItem]:
+    """Remove duplicate WebSearch items.
+
+    Deduplication is based on URL.
+
+    Args:
+        items: List of WebSearchItem objects
+
+    Returns:
+        Deduplicated list
+    """
+    seen_urls = set()
+    result = []
+
+    for item in items:
+        # Normalize URL for comparison
+        url_key = item.url.lower().rstrip("/")
+        if url_key not in seen_urls:
+            seen_urls.add(url_key)
+            result.append(item)
+
+    return result