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>

.claude-plugin/marketplace.json

@@ -11,7 +11,7 @@
     {
       "name": "last30days",
       "description": "Research any topic across Reddit, X, YouTube, TikTok, Instagram, Hacker News, Polymarket, GitHub, and 5+ more sources. AI agent scores by upvotes, likes, and real money - not editors.",
-      "version": "3.2.0",
+      "version": "3.2.1",
       "author": {
         "name": "Matt Van Horn",
         "url": "https://github.com/mvanhorn"

.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "last30days",
-  "version": "3.2.0",
+  "version": "3.2.1",
   "description": "Research any topic across Reddit, X, YouTube, TikTok, Instagram, Hacker News, Polymarket, GitHub, and 5+ more sources. AI agent scores by upvotes, likes, and real money - not editors.",
   "author": {
     "name": "Matt Van Horn",