feat(digg): rename to 'Digg' and bump per-cluster post limits (#372)

* feat(digg): bump POSTS_PER_CLUSTER to 5 and render limit to 3

Match the per-item enrichment cap and inline-display cap used by the
other sources (Reddit, HN, YouTube, TikTok, GitHub all use 5 fetched /
3 displayed). At the previous 3/2 caps the engine routinely truncated
cluster context — a recent run on cli-printing-press lost the Jason
Calacanis quote tweet entirely because the display cut off after Garry
Tan's first two posts.

* feat(digg): rename 'Digg AI 1000' to 'Digg' in user-facing strings

Drop the 'AI 1000' suffix from the footer line, source label, inline
quote attribution ('via Digg'), why_relevant, container, mock title,
SKILL.md source list, and README sources table. Internal code comments
and docstrings still reference the upstream Digg AI 1000 product.

Bumps version to 3.2.1 and adds a CHANGELOG entry covering this rename
and the POSTS_PER_CLUSTER / render-limit bumps from the prior commit.

---------

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>

skills/last30days/scripts/lib/digg.py

@@ -44,8 +44,9 @@ ENRICH_CONFIG = {
     "deep": 5,
 }
 
-# X posts pulled per enriched cluster.
-POSTS_PER_CLUSTER = 3
+# X posts pulled per enriched cluster. Matches the 5-comment cap used by
+# Reddit/HN/YouTube/TikTok/GitHub enrichment.
+POSTS_PER_CLUSTER = 5
 
 SEARCH_TIMEOUT = 30
 POSTS_TIMEOUT = 15
@@ -285,9 +286,9 @@ def parse_digg_response(
                 "posts": [],
                 "relevance": round(relevance, 2),
                 "why_relevant": (
-                    f"Digg AI 1000 cluster (rank {rank}, {post_count} posts, {unique_authors} authors)"
+                    f"Digg cluster (rank {rank}, {post_count} posts, {unique_authors} authors)"
                     if rank is not None
-                    else f"Digg AI 1000 cluster ({post_count} posts, {unique_authors} authors)"
+                    else f"Digg cluster ({post_count} posts, {unique_authors} authors)"
                 ),
             }
         )