chore: jest module resolution fix

Move public/Icons, public/Images, public/Logos, public/svgs to
src/assets/ and replace all string literal asset references across
74 files with ES imports via the @ alias.

Assets are now processed through Vite's module pipeline, making them
content-hashed in dist/ and base-path-aware — prerequisite for the
runtime URL prefix feature (base path).

Known gap: src/ReactI18/index.tsx loadPath still uses absolute /locales/
path — to be fixed in the base path feature PR.

frontend/__mocks__/fileMock.ts

@@ -0,0 +1 @@
+export default 'test-file-stub';

frontend/jest.config.ts

@@ -11,6 +11,9 @@ const config: Config.InitialOptions = {
 	moduleFileExtensions: ['ts', 'tsx', 'js', 'json'],
 	modulePathIgnorePatterns: ['dist'],
 	moduleNameMapper: {
+		'\\.(png|jpg|jpeg|gif|svg|webp|avif|ico|bmp|tiff)$':
+			'<rootDir>/__mocks__/fileMock.ts',
+		'^@/(.*)$': '<rootDir>/src/$1',
 		'\\.(css|less|scss)$': '<rootDir>/__mocks__/cssMock.ts',
 		'\\.md$': '<rootDir>/__mocks__/cssMock.ts',
 		'^uplot$': '<rootDir>/__mocks__/uplotMock.ts',