feat: Haiku-default model routing with Sonnet escalation + Sentry observability

Route ~90% of simple chat to claude-haiku (4x cheaper), escalate to
claude-sonnet for code blocks, long messages, technical keywords,
multimodal, and explicit requests. Sentry tags track model_used,
escalation_reason, and token usage breadcrumbs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -19,6 +19,8 @@ services:
       - LITELLM_BASE_URL
       - LITELLM_API_KEY
       - DEFAULT_MODEL
+      - BASE_MODEL=${BASE_MODEL:-claude-haiku}
+      - ESCALATION_MODEL=${ESCALATION_MODEL:-claude-sonnet}
       - MEMORY_SERVICE_URL=http://memory-service:8090
       - MEMORY_SERVICE_TOKEN
       - PORTAL_URL