feat: Add working hours for natural traffic patterns

Workers check their timezone (from preflight IP geolocation) and current
hour's weight probability to determine availability. This creates natural
traffic patterns - more workers active during peak hours, fewer during
off-peak. Tasks queue up at night and drain during the day.

Migrations:
- 099: working_hours table with hourly weights by profile
- 100: Add timezone column to worker_registry
- 101: Store timezone from preflight IP geolocation
- 102: check_working_hours() function with probability roll

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/migrations/099_working_hours.sql

@@ -0,0 +1,68 @@
+-- Migration: 099_working_hours.sql
+-- Description: Working hours profiles for natural traffic pattern simulation
+-- Created: 2024-12-13
+
+-- Working hours table: defines hourly activity weights to mimic natural traffic
+CREATE TABLE IF NOT EXISTS working_hours (
+  id SERIAL PRIMARY KEY,
+  name VARCHAR(50) UNIQUE NOT NULL,
+  description TEXT,
+
+  -- Hour weights: {"0": 15, "1": 5, ..., "18": 100, ...}
+  -- Value = percent chance to trigger activity that hour (0-100)
+  hour_weights JSONB NOT NULL,
+
+  -- Day-of-week multipliers (0=Sunday, 6=Saturday)
+  -- Optional adjustment for weekend vs weekday patterns
+  dow_weights JSONB DEFAULT '{"0": 90, "1": 100, "2": 100, "3": 100, "4": 100, "5": 110, "6": 95}',
+
+  timezone VARCHAR(50) DEFAULT 'America/Phoenix',
+  enabled BOOLEAN DEFAULT true,
+  created_at TIMESTAMPTZ DEFAULT NOW(),
+  updated_at TIMESTAMPTZ DEFAULT NOW()
+);
+
+-- Seed: Natural traffic pattern based on internet usage research
+-- Optimized for cannabis dispensary browsing (lunch + after-work peaks)
+INSERT INTO working_hours (name, description, timezone, hour_weights) VALUES (
+  'natural_traffic',
+  'Mimics natural user browsing patterns - peaks at lunch and 5-7 PM',
+  'America/Phoenix',
+  '{
+    "0": 15,
+    "1": 5,
+    "2": 5,
+    "3": 5,
+    "4": 5,
+    "5": 10,
+    "6": 20,
+    "7": 30,
+    "8": 35,
+    "9": 45,
+    "10": 50,
+    "11": 60,
+    "12": 75,
+    "13": 65,
+    "14": 60,
+    "15": 70,
+    "16": 80,
+    "17": 95,
+    "18": 100,
+    "19": 100,
+    "20": 90,
+    "21": 70,
+    "22": 45,
+    "23": 25
+  }'::jsonb
+) ON CONFLICT (name) DO UPDATE SET
+  hour_weights = EXCLUDED.hour_weights,
+  description = EXCLUDED.description,
+  updated_at = NOW();
+
+-- Index for quick lookups
+CREATE INDEX IF NOT EXISTS idx_working_hours_name ON working_hours(name);
+CREATE INDEX IF NOT EXISTS idx_working_hours_enabled ON working_hours(enabled);
+
+COMMENT ON TABLE working_hours IS 'Activity profiles for natural traffic simulation. Hour weights are percent chance (0-100) to trigger activity.';
+COMMENT ON COLUMN working_hours.hour_weights IS 'JSON object mapping hour (0-23) to percent chance (0-100). 100 = always run, 0 = never run.';
+COMMENT ON COLUMN working_hours.dow_weights IS 'Optional day-of-week multipliers. 0=Sunday. Applied as (hour_weight * dow_weight / 100).';