Add context windows, web search, streamed answers, overlay move/resize; overhaul docs

- Context windows (contexts/*.yaml) scope answers to a defined domain
- Optional DuckDuckGo web search behind ai.web_search.enabled (default off)
- Stream partial answers into the overlay at first-token time
- Default Whisper to local base.en (~9x faster); offline model loading
- Priority-ordered loopback detection (BlackHole > Teams device)
- Overlay: drag interior to move, edges to resize
- Stop tracking model binaries (models/ is gitignored)
- README/CLAUDE.md overhaul + tracked config.example.yaml

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

.gitignore

@@ -33,12 +33,22 @@ logs/
 *.log
 
 # Configuration files with sensitive data
+# (config.example.yaml is the tracked template — copy it to config.yaml)
 config.yaml
 config/local.yaml
 config/production.yaml
 *.local.yaml
 *.secret.yaml
 
+# Context windows: personal interview/meeting contexts stay private.
+# Only the README and the shipped example are tracked.
+contexts/*
+!contexts/README.md
+!contexts/python_flask_backend.yaml
+
+# Claude Code local settings
+.claude/settings.local.json
+
 # Model files (large binaries — downloaded by setup.py / faster-whisper, not tracked)
 models/