v0.4.15

Added

• magento2-performance-audit: references/database-query-profiling.md documents a
  core-Magento pattern where catalog_product_entity_tier_price/catalogrule_product_price
  fire once per displayed product on category pages, traced initially (wrongly) to a
  project's own pricing plugin — the plugin is structurally identical to core's own
  BasePrice::getValue(). The real mechanism: Layer\Category\CollectionFilter's default
  addFinalPrice() sets tier_price to a scalar/NULL from the price index, which fails
  TierPrice::getStoredTierPrices()'s is_array() check regardless, and
  catalog_rule_price isn't in that join's columns at all. Confirmed on a vanilla install
  (same scaling, 9–24/page) — the count gap was catalog/frontend/grid_per_page being
  ~2x, not a code difference. Includes the "diff an around plugin against core before
  naming it root cause" rule and the hasData()-based batch-load fix.
• magento2-performance-audit: references/code-level-patterns.md adds two short
  false-positive callouts to the existing N+1/collection-counting patterns (a Form
  vs. Grid DataProvider matching the N+1 grep is usually one row, not a scaling bug; a
  count($collection->getItems()) after an earlier foreach on the same instance is
  free, not a live query) and a new "Batch-Preload Plugins Must Stay FPC-Safe" section —
  any SessionManagerInterface-backed session (customer, checkout/quote, not just
  customer group) read inside a batch-preload plugin on a listing block risks starting a
  session for anonymous FPC-cached traffic; read Http\Context instead, the same
  Vary-cookie signal core's own FPC-safe price code uses.

Fixed

• The first draft of both entries above ran long (884 words prose vs. this hub's ~170–220
  word house style for a single lesson) — cut narrative restatement of the correction,
  kept the mechanism, the two verification checks, and the fix code.

Full Changelog: v0.4.14...v0.4.15