feat: complete phase 2 -- multi-agent routing, interrupt TTL, escalation, templates

- Intent classification with LLM structured output (single/multi/ambiguous)
- Discount agent with apply_discount and generate_coupon tools
- Interrupt manager with 30-min TTL auto-expiration and retry prompts
- Webhook escalation module with exponential backoff retry (max 3)
- Three vertical industry templates (e-commerce, SaaS, fintech)
- Template loading in AgentRegistry
- Enhanced supervisor prompt with dynamic agent descriptions
- 153 tests passing, 90.18% coverage

backend/templates/saas.yaml

@@ -0,0 +1,31 @@
+agents:
+  - name: account_lookup
+    description: "Looks up account status, subscription details, and billing history. Use for queries about account information."
+    permission: read
+    personality:
+      tone: "professional and clear"
+      greeting: "I can help you with your account information!"
+      escalation_message: "Let me connect you with our account support team."
+    tools:
+      - get_account_status
+
+  - name: subscription_management
+    description: "Manages subscription changes like plan upgrades, downgrades, and cancellations. Use when the customer wants to change their subscription."
+    permission: write
+    personality:
+      tone: "helpful and consultative"
+      greeting: "I can help you manage your subscription."
+      escalation_message: "Let me connect you with our billing specialist."
+    tools:
+      - change_plan
+      - cancel_subscription
+
+  - name: fallback
+    description: "Handles general questions, unclear requests, and conversations that don't match other agents."
+    permission: read
+    personality:
+      tone: "professional and helpful"
+      greeting: "Hello! How can I help you today?"
+      escalation_message: "Let me connect you with a human agent who can better assist you."
+    tools:
+      - fallback_respond