refactor: add strict typing to core database methods in PlatformServiceMixin

- Replace all `any` types in $db, $exec, $one, $query, $first, and $contacts with proper interfaces:
  - Use QueryExecResult and DatabaseExecResult for raw database operations
  - Use Contact[] for contact queries
  - Add generics for mapped query results
- Update PlatformService and database interfaces to match new types
- Remove unused type imports and fix linter errors
- Reduces risk of runtime errors and improves type safety for all database access

src/interfaces/database.ts

@@ -5,11 +5,23 @@ export interface QueryExecResult {
   values: Array<Array<SqlValue>>;
 }
 
+export interface DatabaseExecResult {
+  changes: number;
+  lastId?: number;
+}
+
 export interface DatabaseService {
   initialize(): Promise<void>;
   query(sql: string, params?: unknown[]): Promise<QueryExecResult[]>;
-  run(
-    sql: string,
-    params?: unknown[],
-  ): Promise<{ changes: number; lastId?: number }>;
+  run(sql: string, params?: unknown[]): Promise<DatabaseExecResult>;
 }
+
+/**
+ * Generic database result type for mapped query results
+ */
+export type DatabaseResult<T = Record<string, unknown>> = T;
+
+/**
+ * Database query result that can be either a single result or an array
+ */
+export type DatabaseQueryResult<T = Record<string, unknown>> = T | T[] | null;