Add domain glossary: Source, source kinds, Briefing

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

GLOSSARY.md

@@ -0,0 +1,27 @@
+# Tagesbyte
+
+A personal app that collects the day's tech news from German and English sources and condenses it with AI, replacing an n8n → Discord workflow.
+
+## Language
+
+**Source**:
+One news feed the app pulls articles from. A publisher may offer several Sources, and one Source can be a subset of another (heise Security within heise online).
+_Avoid_: Feed, publisher, channel
+
+Every Source has exactly one kind:
+
+**News source**:
+A Source whose articles are time-sensitive reports of what happened. Only News sources feed the Briefing.
+_Avoid_: Feed, newsfeed
+
+**Learning source**:
+A Source of evergreen material for building skills or understanding (system design explainers, engineering blogs, research write-ups), worth reading days or weeks after publication.
+_Avoid_: Blog, newsletter, deep dive
+
+**Fun source**:
+A Source of tech humour: comics, memes, IT horror stories.
+_Avoid_: Memes, entertainment
+
+**Briefing**:
+An AI-written digest of the most important stories from News sources over one time window, grouped into topics that link back to their articles.
+_Avoid_: Digest, summary, daily news