Improve SKU catalog hygiene and BOM accuracy

- refresh_sku_catalog.py: add --discover to report API SKUs missing from
  catalog, filtered to already-curated serviceCategory values. Auto-runs
  at end of --validate and --refresh so gaps surface on every maintenance
  pass. First run found 162 missing SKUs (Blackwell GPUs, X12 Ax compute,
  VMware reserved tiers, WebLogic-on-OKE, Analytics/OIC BYOL).
- oci_bom_gen.py: fix Cost % column being blank. Back-fill was gated on
  formula detection but data rows write raw numbers, so the predicate
  never matched. Now tracks data_item_rows explicitly.
- .gitea/workflows/sku-catalog-refresh.yaml: monthly automation (1st at
  09:00 UTC). Auto-refresh prices → push branch + open PR; detect new
  SKUs → open issue with labels. Gated on secrets.GITEA_TOKEN.
- kb/pricing/oci-sku-catalog.yaml: add B95714 / B95715 (Autonomous ATP
  Dedicated ECPU, LI + BYOL) — canonical SKUs for ADB-D pricing.
- kb/services/compute.yaml: add X12 family (VM.Standard4.Ax.Flex,
  BM.Standard4.Ax.120), E6.Ax and A4.Ax variants. Verified against
  docs.oracle.com computeshapes.htm. Bump last_verified + changelog.
- templates/bom-spec.yaml: document 730 hrs/month convention as default
  (= real annual billing / 12; 744 overstates by 1.92% on 12-month TCO).
- Makefile: new 'make sku-discover' target.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Makefile

@@ -1,6 +1,6 @@
 # OCI Deal Accelerator — Build Automation
 
-.PHONY: help install test validate example diagram deck full clean lint codex-package update-icons freshness freshness-refresh sync-skill
+.PHONY: help install test validate example diagram deck full clean lint codex-package update-icons freshness freshness-refresh sync-skill sku-discover
 
 # Use venv if present, otherwise find best available python3
 ifneq (,$(wildcard .venv/bin/python))
@@ -97,3 +97,6 @@ kb-check: ## KB freshness JSON (used by skill welcome-flow pre-flight)
 
 freshness-refresh: ## Run refresh tools for stale KB files that support automation
 	@$(PYTHON) tools/kb_freshness.py --auto-refresh
+
+sku-discover: ## Report SKUs present in Oracle API but missing from oci-sku-catalog.yaml
+	@$(PYTHON) tools/refresh_sku_catalog.py --discover