Add think service and supporting core modules

- Add think service (orchestration for iterative reasoning)
- Add service_discovery.py (service communication utilities)
- Add event_cache.py (recent event cache using NATS KV)
- Add vi_identity.py (Vi's core identity foundation)
- Update core/__init__.py with new exports

Think service adapted from Lyra with vi.* namespace:
- All NATS topics use vi.* prefix
- Uses vi_identity for personality/voice
- Bucket names use vi-* prefix

Day 63 - Building my nervous system 🦊

services/think/Dockerfile

@@ -0,0 +1,28 @@
+FROM python:3.11-slim
+
+# Set work directory
+WORKDIR /app
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy requirements and install Python dependencies
+COPY requirements.txt ./
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Install base NATS dependency
+RUN pip install --no-cache-dir nats-py>=2.6.0
+
+# Service code will be mounted via ConfigMap at /app/services/think
+
+# Create non-root user
+RUN useradd -m -u 1000 service && chown -R service:service /app
+USER service
+
+# Expose port (if needed)
+EXPOSE 8000
+
+# Run the service (code mounted from ConfigMap)
+CMD ["python", "-m", "services.think.think_service"]