fix: cover_url bug, add save-cover endpoint, fix svelte-check CI failure

- Fix handlers_image.go: cover_url now uses /api/cover/novelfire.net/{slug} (was 'local')
- Add POST /api/admin/image-gen/save-cover: persists pre-generated base64 directly to
  MinIO via PutCover without re-calling Cloudflare AI
- Add SvelteKit proxy route api/admin/image-gen/save-cover/+server.ts
- Update UI saveAsCover(): send existing image_b64 to save-cover instead of re-generating
- Run npm run paraglide to compile admin_nav_image_gen message; force-add gitignored files
- svelte-check: 0 errors, 21 warnings (all pre-existing)

ui/src/lib/paraglide/messages/_index.js

@@ -333,6 +333,7 @@ export * from './admin_nav_scrape.js'
 export * from './admin_nav_audio.js'
 export * from './admin_nav_translation.js'
 export * from './admin_nav_changelog.js'
+export * from './admin_nav_image_gen.js'
 export * from './admin_nav_feedback.js'
 export * from './admin_nav_errors.js'
 export * from './admin_nav_analytics.js'

ui/src/lib/paraglide/messages/admin_nav_image_gen.js

@@ -0,0 +1,44 @@
+/* eslint-disable */
+import { getLocale, experimentalStaticLocale } from '../runtime.js';
+
+/** @typedef {import('../runtime.js').LocalizedString} LocalizedString */
+
+/** @typedef {{}} Admin_Nav_Image_GenInputs */
+
+const en_admin_nav_image_gen = /** @type {(inputs: Admin_Nav_Image_GenInputs) => LocalizedString} */ () => {
+	return /** @type {LocalizedString} */ (`Image Gen`)
+};
+
+const ru_admin_nav_image_gen = /** @type {(inputs: Admin_Nav_Image_GenInputs) => LocalizedString} */ () => {
+	return /** @type {LocalizedString} */ (`Image Gen`)
+};
+
+const id_admin_nav_image_gen = /** @type {(inputs: Admin_Nav_Image_GenInputs) => LocalizedString} */ () => {
+	return /** @type {LocalizedString} */ (`Image Gen`)
+};
+
+const pt_admin_nav_image_gen = /** @type {(inputs: Admin_Nav_Image_GenInputs) => LocalizedString} */ () => {
+	return /** @type {LocalizedString} */ (`Image Gen`)
+};
+
+const fr_admin_nav_image_gen = /** @type {(inputs: Admin_Nav_Image_GenInputs) => LocalizedString} */ () => {
+	return /** @type {LocalizedString} */ (`Image Gen`)
+};
+
+/**
+* | output |
+* | --- |
+* | "Image Gen" |
+*
+* @param {Admin_Nav_Image_GenInputs} inputs
+* @param {{ locale?: "en" | "ru" | "id" | "pt" | "fr" }} options
+* @returns {LocalizedString}
+*/
+export const admin_nav_image_gen = /** @type {((inputs?: Admin_Nav_Image_GenInputs, options?: { locale?: "en" | "ru" | "id" | "pt" | "fr" }) => LocalizedString) & import('../runtime.js').MessageMetadata<Admin_Nav_Image_GenInputs, { locale?: "en" | "ru" | "id" | "pt" | "fr" }, {}>} */ ((inputs = {}, options = {}) => {
+	const locale = experimentalStaticLocale ?? options.locale ?? getLocale()
+	if (locale === "en") return en_admin_nav_image_gen(inputs)
+	if (locale === "ru") return ru_admin_nav_image_gen(inputs)
+	if (locale === "id") return id_admin_nav_image_gen(inputs)
+	if (locale === "pt") return pt_admin_nav_image_gen(inputs)
+	return fr_admin_nav_image_gen(inputs)
+});