fix: Odoo 18 field errors, routing quality, bot presence, and add architecture docs

- expenses_tools: remove 'date' from hr.expense.sheet field lists (Odoo 18
  uses accounting_date; querying 'date' raised ValueError at runtime)
- master_system.txt: add few-shot routing examples so Llama 3.1 8B correctly
  outputs agents=[] for general questions instead of defaulting to expenses_agent
- ab_ai_bot.py: increase bot presence last_poll offset from 90s to 10min so
  the green dot stays on between cron runs (cron fires every ~5min in practice,
  not every 20s as configured)
- ARCHITECTURE.md: full system documentation covering component layout, request
  flow, LLM routing, agent registry, access control, health/presence mechanism,
  known issues fixed today, and future self-healing concept

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

addons/activeblue_ai/models/ab_ai_bot.py

@@ -175,11 +175,11 @@ class AbAiBot(models.Model):
             Presence = self.env['bus.presence']
             now = fields.Datetime.now()
             # bus.presence.status is a computed field — write only last_poll/last_presence.
-            # When online: set last_poll 90s ahead so the bot stays "online" across the
-            # full 60s cron cycle (Odoo DISCONNECTION_TIMER is 30s).
+            # When online: set last_poll 10min ahead so the bot stays "online" across
+            # the full cron cycle (Odoo cron scheduler fires every ~5min in practice).
             # When offline: set last_poll an hour in the past to force "offline" state.
             if online:
-                poll_time = now + timedelta(seconds=90)
+                poll_time = now + timedelta(minutes=10)
                 presence_time = now
             else:
                 poll_time = now - timedelta(hours=1)