feat(scheduler): Immutable schedules and HTTP-only pipeline

## Changes
- **Migration 089**: Add is_immutable and method columns to task_schedules
  - Per-state product_discovery schedules (4h default)
  - Store discovery weekly (168h)
  - All schedules use HTTP transport (Puppeteer/browser)
- **Task Scheduler**: HTTP-only product discovery with per-state scheduling
  - Each state has its own immutable schedule
  - Schedules can be edited (interval/priority) but not deleted
- **TasksDashboard UI**: Full immutability support
  - Lock icon for immutable schedules
  - State and Method columns in schedules table
  - Disabled delete for immutable, restricted edit fields
- **Store Discovery HTTP**: Auto-queue product_discovery for new stores
- **Migration 088**: Discovery payloads storage schema

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

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

backend/migrations/089_immutable_schedules.sql

@@ -0,0 +1,105 @@
+-- Migration 089: Immutable Schedules with Per-State Product Discovery
+--
+-- Key changes:
+-- 1. Add is_immutable column - schedules can be edited but not deleted
+-- 2. Add method column - all tasks use 'http' (Puppeteer transport)
+-- 3. Store discovery weekly (168h)
+-- 4. Per-state product_discovery schedules (4h default)
+-- 5. Remove old payload_fetch schedules
+
+-- =====================================================
+-- 1) Add new columns to task_schedules
+-- =====================================================
+ALTER TABLE task_schedules
+ADD COLUMN IF NOT EXISTS is_immutable BOOLEAN DEFAULT FALSE;
+
+ALTER TABLE task_schedules
+ADD COLUMN IF NOT EXISTS method VARCHAR(10) DEFAULT 'http';
+
+-- =====================================================
+-- 2) Update store_discovery to weekly and immutable
+-- =====================================================
+UPDATE task_schedules
+SET interval_hours = 168,  -- 7 days
+    is_immutable = TRUE,
+    method = 'http',
+    description = 'Discover new Dutchie stores weekly (HTTP transport)'
+WHERE name = 'store_discovery_dutchie';
+
+-- Insert if doesn't exist
+INSERT INTO task_schedules (name, role, interval_hours, priority, description, is_immutable, method, platform, next_run_at)
+VALUES ('store_discovery_dutchie', 'store_discovery', 168, 5, 'Discover new Dutchie stores weekly (HTTP transport)', TRUE, 'http', 'dutchie', NOW())
+ON CONFLICT (name) DO UPDATE SET
+  interval_hours = 168,
+  is_immutable = TRUE,
+  method = 'http',
+  description = 'Discover new Dutchie stores weekly (HTTP transport)';
+
+-- =====================================================
+-- 3) Remove old payload_fetch and product_refresh_all schedules
+-- =====================================================
+DELETE FROM task_schedules WHERE name IN ('payload_fetch_all', 'product_refresh_all');
+
+-- =====================================================
+-- 4) Create per-state product_discovery schedules
+-- =====================================================
+-- One schedule per state that has dispensaries with active cannabis programs
+INSERT INTO task_schedules (name, role, state_code, interval_hours, priority, description, is_immutable, method, enabled, next_run_at)
+SELECT
+  'product_discovery_' || lower(s.code) AS name,
+  'product_discovery' AS role,
+  s.code AS state_code,
+  4 AS interval_hours,  -- 4 hours default, editable
+  10 AS priority,
+  'Product discovery for ' || s.name || ' dispensaries (HTTP transport)' AS description,
+  TRUE AS is_immutable,  -- Can edit but not delete
+  'http' AS method,
+  CASE WHEN s.is_active THEN TRUE ELSE FALSE END AS enabled,
+  -- Stagger start times: each state starts 5 minutes after the previous
+  NOW() + (ROW_NUMBER() OVER (ORDER BY s.code) * INTERVAL '5 minutes') AS next_run_at
+FROM states s
+WHERE EXISTS (
+  SELECT 1 FROM dispensaries d
+  WHERE d.state_id = s.id AND d.crawl_enabled = true
+)
+ON CONFLICT (name) DO UPDATE SET
+  is_immutable = TRUE,
+  method = 'http',
+  description = EXCLUDED.description;
+
+-- Also create schedules for states that might have stores discovered later
+INSERT INTO task_schedules (name, role, state_code, interval_hours, priority, description, is_immutable, method, enabled, next_run_at)
+SELECT
+  'product_discovery_' || lower(s.code) AS name,
+  'product_discovery' AS role,
+  s.code AS state_code,
+  4 AS interval_hours,
+  10 AS priority,
+  'Product discovery for ' || s.name || ' dispensaries (HTTP transport)' AS description,
+  TRUE AS is_immutable,
+  'http' AS method,
+  FALSE AS enabled,  -- Disabled until stores exist
+  NOW() + INTERVAL '1 hour'
+FROM states s
+WHERE NOT EXISTS (
+  SELECT 1 FROM task_schedules ts WHERE ts.name = 'product_discovery_' || lower(s.code)
+)
+ON CONFLICT (name) DO NOTHING;
+
+-- =====================================================
+-- 5) Make analytics_refresh immutable
+-- =====================================================
+UPDATE task_schedules
+SET is_immutable = TRUE, method = 'http'
+WHERE name = 'analytics_refresh';
+
+-- =====================================================
+-- 6) Add index for schedule lookups
+-- =====================================================
+CREATE INDEX IF NOT EXISTS idx_task_schedules_state_code
+  ON task_schedules(state_code)
+  WHERE state_code IS NOT NULL;
+
+-- Comments
+COMMENT ON COLUMN task_schedules.is_immutable IS 'If TRUE, schedule cannot be deleted (only edited)';
+COMMENT ON COLUMN task_schedules.method IS 'Transport method: http (Puppeteer/browser) or curl (axios)';