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>

run.sh

@@ -25,11 +25,14 @@ else
     echo "   Run: python3 -m venv .venv && source .venv/bin/activate && pip install -r requirements.txt"
 fi
 
-# Install PortAudio if needed (macOS)
+# Install PortAudio if needed (macOS). Skip Homebrew's auto-update (slow/can fail
+# behind restricted networks) and never let a brew hiccup abort the launcher —
+# PortAudio is usually already present.
 if [[ "$OSTYPE" == "darwin"* ]]; then
+    export HOMEBREW_NO_AUTO_UPDATE=1
     if command -v brew &> /dev/null && ! brew list portaudio &> /dev/null 2>&1; then
         echo "📦 Installing PortAudio via Homebrew..."
-        brew install portaudio
+        brew install portaudio || echo "⚠️  PortAudio install failed — continuing (may already be present)"
     fi
 fi