Feature/post media translations (#42)

* chore: updated todo with translation ideas

* feat: first take at the implementation of translations

* fix: small addition for the translation feature

* feat: support language switching in the editor and preview

* feat: better handling of long bodies by not running them through a json envelope

* fix: unknown macros have better fallback

* feat: api for python to get translations

* fix: strip dumb prefix of content in translation

* feat: extend meta diff for translations

* feat: hook up translations to rebuild-from-disk

* feat: generation of the website prefers project language, falling back to canonical language

* fix: crashes during rendering

* feat: translation validation report

* fix: made the translation validation actually work

* chore: reorganization of menu

* fix: some topics cleanup

* chore: updated doc

* feat: translations for media

* feat: more aligned in UI/UX

* feat: edit translations possible

* chore: added full multi-language todo

* chore: updated todo for clarity

* feat: implementation of full multi-linguality

* fix: page creation creates pages

* fix: flags on every page

* fix: better prompt

* feat: made MCP server aware of language content

* feat: python tools for translations

* fix: better fill-in-translations

* fix: better prompt for translation. maybe.

* fix: losing posts from search due to translation process

* fix: translation validation handles in-db content and fill-in of missing translations fixed to flush

* fix: faster scanning for infilling of missing translations

* chore: updated agent instructions

* feat: calendar and tag cloud respect current language now

* fix: retries going up

* fix: got metadata-diff and rebuild into sync

* fix: extended meta-diff for timestamps

* fix: made website validation look at translated content, too

* fix: multi-lingual search

* chore: refactor Editor.tsx into two separate editors

* feat: do language detection when no explicit language given

---------

Co-authored-by: hugo <hugoms@me.com>

src/main/engine/MetaEngine.ts

@@ -6,6 +6,7 @@ import { eq } from 'drizzle-orm';
 import { getDatabase } from '../database';
 import { posts, projects } from '../database/schema';
 import { sanitizePicoTheme, type PicoThemeName } from '../shared/picoThemes';
+import { SUPPORTED_RENDER_LANGUAGES, type SupportedLanguage } from '../shared/i18n';
 import {
   normalizeTaxonomyTerm,
   normalizeNonEmptyTaxonomyTerm,
@@ -29,6 +30,7 @@ export interface ProjectMetadata {
   categoryMetadata?: Record<string, CategoryMetadata>; // Per-category metadata for UI/rendering
   categorySettings?: Record<string, CategoryRenderSettings>; // Per-category list rendering preferences
   semanticSimilarityEnabled?: boolean; // Enable local ONNX embedding-based semantic similarity
+  blogLanguages?: string[]; // Languages the blog is rendered in (mainLanguage is always included)
 }
 
 export interface CategoryRenderSettings {
@@ -103,6 +105,19 @@ function sanitizeCategoryTitle(value: unknown, fallback: string): string {
 
 type RawCategoryMetadataInput = Record<string, CategoryMetadata | CategoryRenderSettings>;
 
+const supportedLanguageSet = new Set<string>(SUPPORTED_RENDER_LANGUAGES);
+
+function sanitizeBlogLanguages(value: unknown): string[] | undefined {
+  if (!Array.isArray(value)) {
+    return undefined;
+  }
+  const filtered = value
+    .filter((item): item is string => typeof item === 'string')
+    .map((item) => item.trim().toLowerCase())
+    .filter((item) => item.length > 0 && supportedLanguageSet.has(item));
+  return filtered.length > 0 ? [...new Set(filtered)] : undefined;
+}
+
 function normalizeProjectMetadata(metadata: ProjectMetadata): ProjectMetadata {
   const maxPostsPerPage = sanitizeMaxPostsPerPage(metadata.maxPostsPerPage);
   const publicUrl = sanitizePublicUrl(metadata.publicUrl);
@@ -112,6 +127,7 @@ function normalizeProjectMetadata(metadata: ProjectMetadata): ProjectMetadata {
   const pythonRuntimeMode = metadata.pythonRuntimeMode === 'main-thread' ? 'main-thread' : 'webworker';
   const picoTheme = sanitizePicoTheme(metadata.picoTheme);
   const categoryMetadata = normalizeCategoryMetadata(metadata.categoryMetadata ?? metadata.categorySettings);
+  const blogLanguages = sanitizeBlogLanguages(metadata.blogLanguages);
   return {
     ...metadata,
     publicUrl,
@@ -121,6 +137,7 @@ function normalizeProjectMetadata(metadata: ProjectMetadata): ProjectMetadata {
     picoTheme,
     categoryMetadata,
     categorySettings: undefined,
+    blogLanguages,
   };
 }
 
@@ -349,6 +366,7 @@ export class MetaEngine extends EventEmitter {
         picoTheme: normalizedUpdates.picoTheme,
         categoryMetadata: normalizedUpdates.categoryMetadata,
         semanticSimilarityEnabled: normalizedUpdates.semanticSimilarityEnabled,
+        blogLanguages: normalizedUpdates.blogLanguages,
       });
     } else {
       this.projectMetadata = normalizeProjectMetadata({