Remove legacy TypeScript financial surface mapping, make Rust JSON single source of truth

- Delete standard-template.ts, surface.ts, materialize.ts (dead code)
- Delete financial-taxonomy.test.ts (relied on removed code)
- Add missing income statement surfaces to core.surface.json
- Add cost_of_revenue mapping to core.income-bridge.json
- Refactor standardize.ts to remove template dependency
- Simplify financial-taxonomy.ts to use only DB snapshots
- Add architecture documentation

lib/server/financial-taxonomy.ts

@@ -36,8 +36,7 @@ import {
 } from '@/lib/server/financials/bundles';
 import {
   buildDimensionBreakdown,
-  buildLtmStandardizedRows,
-  buildStandardizedRows
+  buildLtmStandardizedRows
 } from '@/lib/server/financials/standardize';
 import { buildRatioRows } from '@/lib/server/financials/ratios';
 import { buildFinancialCategories, buildTrendSeries } from '@/lib/server/financials/trend-series';
@@ -620,16 +619,7 @@ function buildQuarterlyStatementSurfaceRows(input: {
     selectedPeriodIds: input.selectedPeriodIds
   });
 
-  if (aggregatedRows.length > 0) {
-    return aggregatedRows;
-  }
-
-  return buildStandardizedRows({
-    rows: input.faithfulRows,
-    statement: input.statement,
-    periods: input.sourcePeriods,
-    facts: input.facts
-  }) as SurfaceFinancialRow[];
+  return aggregatedRows;
 }
 
 function aggregatePersistedKpiRows(input: {
@@ -1303,7 +1293,6 @@ export async function getCompanyFinancialTaxonomy(input: GetCompanyFinancialsInp
 
 export const __financialTaxonomyInternals = {
   buildRows,
-  buildStandardizedRows,
   buildDimensionBreakdown,
   buildNormalizationMetadata,
   aggregateSurfaceRows,