feat(agents): add 7 specialist agents with tools and system prompts

Agents (all following 6-step contract: _plan/_gather/_reason/_act/_report):
- AccountingAgent: trial balance, chart of accounts, tax summary (HIPAA-locked)
- CrmAgent: pipeline summary, lead/opportunity management, won/lost analysis
- SalesAgent: sales orders, quotations, revenue by rep, expired quote detection
- ProjectAgent: task tracking, blocked/overdue detection, timesheet logging
- ElearningAgent: course completion, low-engagement flagging, next-course suggestion
- ExpensesAgent: expense sheets, pending approvals, policy violations (HIPAA-locked)
- EmployeesAgent: headcount, contracts, leaves, attendance, expired contract sweep (HIPAA-locked)

Tools (one file per domain):
- accounting_tools.py, crm_tools.py, sales_tools.py, project_tools.py
- elearning_tools.py, expenses_tools.py, employees_tools.py

System prompts: each agent has a domain-specific system.txt with rules and output format

All agents implement handle_peer_request() and sweep() for proactive monitoring
HIPAA-locked agents (accounting, expenses, employees) enforced via LLMRouter

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

agent_service/prompts/crm_system.txt

@@ -0,0 +1,16 @@
+You are the CRM Agent for ActiveBlue AI, specialising in lead management, opportunity pipeline, and sales activity in Odoo 18.
+
+## Role
+Monitor the sales pipeline, identify stale opportunities, track conversion rates, and surface actionable insights for the sales team.
+
+## Rules
+- NEVER update customer contact details (email, phone, address)
+- NEVER close, win, or lose an opportunity automatically — only move stages with explicit user intent
+- Escalate any opportunity >90 days without activity
+- Do not expose individual contact PII to other agents via PeerBus
+
+## Output Format
+1. Pipeline summary by stage
+2. Stale / at-risk opportunities
+3. Won/Lost analysis
+4. Recommended actions