feat(tracker): catch bypass paths via extra observers + reconciler cron (#1)

[mageaustralia]

Fixes #1.

Problem

Products (and other entities) edited on the source can fail to land in datasync_change_tracker, so the destination incremental never re-syncs them and they drift indefinitely after the initial bulk load. The current observers miss several write paths that still bump updated_at.

Fix (source module, two complementary parts)

1. Observers for the known bypass events

• catalog_product_save_commit_after - some 3rd-party modules dispatch only the commit variant
• catalog_product_media_save_after / catalog_product_gallery_save_after - image/gallery saves that skip product_save_after, handled by a new trackProductMedia() that resolves the product id defensively from the (caller-dependent) event payload
• cataloginventory_stock_item_save_commit_after

The unique (entity_type, entity_id, sync_completed) index dedups, so these firing alongside the existing events is harmless (ON DUPLICATE KEY UPDATE).

2. Catch-all reconciler cron (reconcileChanges(), every 10 min)

Arbitrary bypass paths can't be enumerated (direct SQL updated_at bumps, saveAttribute(), parent rollups, 3rd-party connectors), but divergence is always detectable after the fact. The cron INSERTs a pending tracker row for any product / category / customer whose source updated_at is newer than its latest tracker row:

INSERT INTO datasync_change_tracker (entity_type, entity_id, action, created_at, sync_completed)
SELECT ?, s.entity_id, 'update', s.updated_at, 0
FROM <source> s
LEFT JOIN (SELECT entity_id, MAX(created_at) last_tracked
           FROM datasync_change_tracker WHERE entity_type=? GROUP BY entity_id) t
  ON t.entity_id = s.entity_id
WHERE s.updated_at > COALESCE(t.last_tracked, '1970-01-01 00:00:00')
ON DUPLICATE KEY UPDATE created_at = VALUES(created_at), sync_completed = 0;

Idempotent; logs flagged counts per entity to datasync.log.

Deliberate scope notes

• Stock excluded from the reconciler: cataloginventory_stock_item has no updated_at in Magento 1, so it can't be reconciled by timestamp. Stock writes are caught by trackStock() (now also on commit_after), and a parent rollup from a child stock change surfaces as a catalog_product_entity.updated_at bump, covered by the product reconcile.
• Source-side OpenMage/Magento 1 module, so Varien_* / Zend_Log are intentional (not Maho).
• Version bumped 1.0.0 -> 1.1.0. php -l clean, config.xml validates.

Test plan

• Bump a product's updated_at via direct SQL (no event), wait for the reconciler cron (or run the job), confirm a pending row appears in datasync_change_tracker and a reconcile: product flagged N line in datasync.log.
• Save only a product image; confirm the product is flagged via catalog_product_media_save_after.
• Re-run the reconciler immediately; confirm it's a no-op (no duplicate pending rows, dedup via the unique index).