Add Columbia catalog mapper, shared upsert, and sync service

Phase 2: the mapping and sync core.

- ColumbiaCatalogMapper (pure/static, unit-tested): maps an API product to a
  PowderCatalogItem. Derives manufacturer (PPG/KP Pigments/Columbia) from
  taxonomy+SKU; flags additives into the Powder Additives category; takes base
  price from the top-level price with variant fallback; captures variation /
  tiered pricing as JSON; parses the free-text cure schedule into all curves
  (three degree glyphs, @/at, multi-curve in order, partial-cure -> none) with
  the first as the primary temp/time; strips HTML descriptions; joins color
  groups; normalizes chemistry; flags clear-coat powders.

- PowderCatalogUpsertService (IPowderCatalogUpsertService): single upsert path
  matching on (VendorName, SKU). Copies only feed-sourced fields and leaves
  enrichment fields (specific gravity, coverage, transfer efficiency, finish)
  untouched so syncs never wipe lazily-enriched TDS/AI data.

- ColumbiaCatalogSyncService (IColumbiaCatalogSyncService): pulls the full
  catalog, maps + de-dupes, upserts, then reconciles discontinuations ONLY on a
  complete pull (a partial pull throws and aborts before the sweep). Reactivates
  reappearing items; records last-synced/last-result platform settings.

- 25 mapper unit tests covering the cure parser, manufacturer derivation,
  simple/variable pricing, chemistry, color, and HTML cases from real records.
  Full suite green (261 passed).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/PowderCoating.Web/Program.cs

@@ -11,6 +11,7 @@ using PowderCoating.Core.Interfaces.Services;
 using PowderCoating.Infrastructure.Data;
 using PowderCoating.Infrastructure.Repositories;
 using PowderCoating.Infrastructure.Services;
+using PowderCoating.Infrastructure.Services.Columbia;
 using PowderCoating.Application.Interfaces;
 using PowderCoating.Application.Services;
 using PowderCoating.Application.Configuration;
@@ -223,6 +224,8 @@ builder.Services.AddScoped<ICustomFormulaAiService, CustomFormulaAiService>();
 builder.Services.AddScoped<IFormulaLibraryService, FormulaLibraryService>();
 builder.Services.AddHttpClient();
 builder.Services.AddScoped<IColumbiaCoatingsApiClient, ColumbiaCoatingsApiClient>();
+builder.Services.AddScoped<IPowderCatalogUpsertService, PowderCatalogUpsertService>();
+builder.Services.AddScoped<IColumbiaCatalogSyncService, ColumbiaCatalogSyncService>();
 builder.Services.AddScoped<ICompanyLogoService, CompanyLogoService>();
 builder.Services.AddScoped<IEquipmentManualService, EquipmentManualService>();
 builder.Services.AddScoped<IPricingCalculationService, PricingCalculationService>();