fix: port search and dimension safety guardrails

- enforce canonical dimensions across app and MCP surfaces
- prioritize title-first node search in UI and query tools
- add regression tests for ranking and dimension validation

src/services/database/dimensionValidation.ts

@@ -0,0 +1,29 @@
+import { getSQLiteClient } from './sqlite-client';
+import { normalizeDimensionName } from './quality';
+
+export function getUnknownDimensions(values: string[]): string[] {
+  if (values.length === 0) return [];
+
+  const sqlite = getSQLiteClient();
+  const placeholders = values.map(() => '?').join(', ');
+  const result = sqlite.query<{ name: string }>(
+    `SELECT name FROM dimensions WHERE name IN (${placeholders})`,
+    values
+  );
+
+  const existing = new Set(
+    result.rows
+      .map(row => (typeof row.name === 'string' ? normalizeDimensionName(row.name) : ''))
+      .filter(Boolean)
+  );
+
+  return values.filter(value => !existing.has(normalizeDimensionName(value)));
+}
+
+export function formatUnknownDimensionsError(values: string[]): string {
+  if (values.length === 1) {
+    return `Unknown dimension: "${values[0]}". Create it first or use an existing dimension.`;
+  }
+
+  return `Unknown dimensions: ${values.map(value => `"${value}"`).join(', ')}. Create them first or use existing dimensions.`;
+}