feat: add cross-database entity lookup for searching column values across all databases

Enables searching for a specific column value (e.g. carrier_id=123) across all databases on a PostgreSQL server. The backend creates temporary connection pools per database (semaphore-limited to 5), queries information_schema for matching columns, and executes read-only SELECTs with real-time progress events. Results are grouped by database/table in a new "Entity Lookup" tab.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/types/index.ts

@@ -216,15 +216,67 @@ export interface SavedQuery {
   created_at: string;
 }
 
-export type TabType = "query" | "table" | "structure" | "roles" | "sessions";
+export interface AiSettings {
+  ollama_url: string;
+  model: string;
+}
+
+export interface OllamaModel {
+  name: string;
+}
+
+// Entity Lookup
+export interface LookupTableMatch {
+  schema: string;
+  table: string;
+  column_type: string;
+  columns: string[];
+  types: string[];
+  rows: unknown[][];
+  row_count: number;
+  total_count: number;
+}
+
+export interface LookupDatabaseResult {
+  database: string;
+  tables: LookupTableMatch[];
+  error: string | null;
+  search_time_ms: number;
+}
+
+export interface EntityLookupResult {
+  column_name: string;
+  value: string;
+  databases: LookupDatabaseResult[];
+  total_databases_searched: number;
+  total_tables_matched: number;
+  total_rows_found: number;
+  total_time_ms: number;
+}
+
+export interface LookupProgress {
+  lookup_id: string;
+  database: string;
+  status: string;
+  tables_found: number;
+  rows_found: number;
+  error: string | null;
+  completed: number;
+  total: number;
+}
+
+export type TabType = "query" | "table" | "structure" | "roles" | "sessions" | "lookup";
 
 export interface Tab {
   id: string;
   type: TabType;
   title: string;
   connectionId: string;
+  database?: string;
   schema?: string;
   table?: string;
   sql?: string;
   roleName?: string;
+  lookupColumn?: string;
+  lookupValue?: string;
 }