Update runtime state and ignore generated media and analytics

Runtime state written by the app: session checkpoint, used-topics history,
regulars, intern lookups, voicemails, publish state through episode 58, and the
website clips index.

Also ignores what should never enter history: clips/, music/, mlx_models/,
remotion-demo/ and social_posts/ come to roughly 13 GB of media and model
weights, and data/costs.db is a binary SQLite database that cost_tracker
rewrites on every LLM call — committing it would attach a multi-megabyte delta
to future commits. cost_reports/ and avatars/ are regenerable, and reaper/peaks/
is a waveform cache.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitignore

@@ -65,3 +65,20 @@ upload-history.json
 
 # Scratch/smoke tests (not committed)
 scratch/
+
+# Generated media and model weights (~13GB — never commit)
+clips/
+music/
+mlx_models/
+remotion-demo/
+social_posts/
+
+# Generated analytics artifacts (rebuilt from cost_tracker)
+data/costs.db
+data/cost_reports/
+
+# Generated caller avatars
+data/avatars/
+
+# Reaper waveform peak cache
+reaper/peaks/