Add kids news channel; document per-source language filter

- New kids channel (/kids) with theme color, surfaced in the web UI
  and routed to by BBC Newsround, DOGO News, Science News Explores,
  and NASA for Students in the example config.
- README and config.example.toml now mention the optional
  per-source `language` filter added in the previous commit.

config.example.toml

@@ -34,6 +34,10 @@ base_url = "https://news.parodia.dev"
 
 # Every enabled source MUST set direct_route to a key from [matrix.channels] above.
 # There is no automatic classification — Pete posts each story to its configured channel.
+# Optional: language = "en" drops feed items whose per-item <language> tag is
+# set and doesn't match (prefix). Useful for multilingual feeds like Politico
+# Europe that publish the same story in en / fr / de side-by-side. Items with
+# no language tag pass through unchanged.
 [[sources]]
 name = "The Guardian — World"
 feed_url = "https://www.theguardian.com/world/rss"
@@ -114,6 +118,38 @@ poll_interval_minutes = 60
 direct_route = "music"
 enabled = true
 
+[[sources]]
+name = "BBC Newsround"
+feed_url = "http://feeds.bbci.co.uk/newsround/rss.xml"
+tier = 1
+poll_interval_minutes = 30
+direct_route = "kids"
+enabled = true
+
+[[sources]]
+name = "DOGO News"
+feed_url = "https://www.dogonews.com/articles.rss"
+tier = 1
+poll_interval_minutes = 60
+direct_route = "kids"
+enabled = true
+
+[[sources]]
+name = "Science News Explores"
+feed_url = "https://www.snexplores.org/feed"
+tier = 1
+poll_interval_minutes = 60
+direct_route = "kids"
+enabled = true
+
+[[sources]]
+name = "NASA for Students"
+feed_url = "https://www.nasa.gov/rss/dyn/educationnews.rss"
+tier = 1
+poll_interval_minutes = 60
+direct_route = "kids"
+enabled = true
+
 [[sources]]
 name = "Post-Punk.com"
 feed_url = "https://post-punk.com/feed/"