feat(cms): add language field + seo_head to manual article creation

- Add language selector (en/de) to article create/edit form
- Store language and generated seo_head in articles table on CREATE and UPDATE
- Write HTML build to BUILD_DIR/{lang}/{slug}.html (consistent with pSEO)
- article_detail.html: render article.seo_head when present (canonical,
  hreflang, OG, JSON-LD Article) — falls back to inline for legacy articles

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

web/src/padelnomics/admin/routes.py

@@ -31,6 +31,42 @@ from ..core import (
     slugify,
 )
 
+def _build_article_seo_head(
+    url_path: str,
+    title: str,
+    meta_desc: str,
+    language: str,
+    published_at: str,
+    *,
+    base_url: str = "https://padelnomics.io",
+) -> str:
+    """Build SEO head block (canonical, OG, JSON-LD) for a manually created article."""
+    def _esc(text: str) -> str:
+        return text.replace("&", "&amp;").replace('"', "&quot;").replace("<", "&lt;")
+
+    full_url = f"{base_url}/{language}{url_path}"
+    jsonld = json.dumps({
+        "@context": "https://schema.org",
+        "@type": "Article",
+        "headline": title[:110],
+        "description": meta_desc[:200],
+        "url": full_url,
+        "inLanguage": language,
+        "datePublished": published_at,
+        "dateModified": published_at,
+        "author": {"@type": "Organization", "name": "Padelnomics", "url": "https://padelnomics.io"},
+        "publisher": {"@type": "Organization", "name": "Padelnomics", "url": "https://padelnomics.io"},
+    }, ensure_ascii=False)
+    return "\n".join([
+        f'<link rel="canonical" href="{full_url}" />',
+        f'<meta property="og:title" content="{_esc(title)}" />',
+        f'<meta property="og:description" content="{_esc(meta_desc)}" />',
+        f'<meta property="og:url" content="{full_url}" />',
+        '<meta property="og:type" content="article" />',
+        f'<script type="application/ld+json">{jsonld}</script>',
+    ])
+
+
 # Blueprint with its own template folder
 bp = Blueprint(
     "admin",
@@ -1716,6 +1752,7 @@ async def article_new():
         country = form.get("country", "").strip()
         region = form.get("region", "").strip()
         body = form.get("body", "").strip()
+        language = form.get("language", "en").strip() or "en"
         status = form.get("status", "draft")
         published_at = form.get("published_at", "").strip()
 
@@ -1731,9 +1768,9 @@ async def article_new():
         body_html = mistune.html(body)
         body_html = await bake_scenario_cards(body_html)
 
-        BUILD_DIR.mkdir(parents=True, exist_ok=True)
+        build_dir = BUILD_DIR / language
-        build_path = BUILD_DIR / f"{article_slug}.html"
+        build_dir.mkdir(parents=True, exist_ok=True)
-        build_path.write_text(body_html)
+        (build_dir / f"{article_slug}.html").write_text(body_html)
 
         # Save markdown source
         md_dir = Path("data/content/articles")
@@ -1741,14 +1778,15 @@ async def article_new():
         (md_dir / f"{article_slug}.md").write_text(body)
 
         pub_dt = published_at or datetime.utcnow().isoformat()
+        seo_head = _build_article_seo_head(url_path, title, meta_description, language, pub_dt)
 
         await execute(
             """INSERT INTO articles
                (url_path, slug, title, meta_description, og_image_url,
-                country, region, status, published_at)
+                country, region, language, status, published_at, seo_head)
-               VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)""",
+               VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
             (url_path, article_slug, title, meta_description, og_image_url,
-             country, region, status, pub_dt),
+             country, region, language, status, pub_dt, seo_head),
         )
         from ..sitemap import invalidate_sitemap_cache
         invalidate_sitemap_cache()
@@ -1780,6 +1818,7 @@ async def article_edit(article_id: int):
         country = form.get("country", "").strip()
         region = form.get("region", "").strip()
         body = form.get("body", "").strip()
+        language = form.get("language", article.get("language", "en")).strip() or "en"
         status = form.get("status", article["status"])
         published_at = form.get("published_at", "").strip()
 
@@ -1793,8 +1832,9 @@ async def article_edit(article_id: int):
         if body:
             body_html = mistune.html(body)
             body_html = await bake_scenario_cards(body_html)
-            BUILD_DIR.mkdir(parents=True, exist_ok=True)
+            build_dir = BUILD_DIR / language
-            (BUILD_DIR / f"{article['slug']}.html").write_text(body_html)
+            build_dir.mkdir(parents=True, exist_ok=True)
+            (build_dir / f"{article['slug']}.html").write_text(body_html)
 
             md_dir = Path("data/content/articles")
             md_dir.mkdir(parents=True, exist_ok=True)
@@ -1802,14 +1842,16 @@ async def article_edit(article_id: int):
 
         now = datetime.utcnow().isoformat()
         pub_dt = published_at or article["published_at"]
+        seo_head = _build_article_seo_head(url_path, title, meta_description, language, pub_dt)
 
         await execute(
             """UPDATE articles
                SET title = ?, url_path = ?, meta_description = ?, og_image_url = ?,
-                   country = ?, region = ?, status = ?, published_at = ?, updated_at = ?
+                   country = ?, region = ?, language = ?, status = ?, published_at = ?,
+                   seo_head = ?, updated_at = ?
                WHERE id = ?""",
             (title, url_path, meta_description, og_image_url,
-             country, region, status, pub_dt, now, article_id),
+             country, region, language, status, pub_dt, seo_head, now, article_id),
         )
         await flash("Article updated.", "success")
         return redirect(url_for("admin.articles"))

web/src/padelnomics/admin/templates/admin/article_form.html

@@ -60,7 +60,14 @@
         <p class="form-hint">Use [scenario:slug] to embed scenario widgets. Sections: :capex, :operating, :cashflow, :returns, :full</p>
       </div>
 
-      <div style="display: grid; grid-template-columns: 1fr 1fr; gap: 1rem;" class="mb-4">
+      <div style="display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 1rem;" class="mb-4">
+        <div>
+          <label class="form-label" for="language">Language</label>
+          <select id="language" name="language" class="form-input">
+            <option value="en" {% if data.get('language', 'en') == 'en' %}selected{% endif %}>English (en)</option>
+            <option value="de" {% if data.get('language') == 'de' %}selected{% endif %}>German (de)</option>
+          </select>
+        </div>
         <div>
           <label class="form-label" for="status">Status</label>
           <select id="status" name="status" class="form-input">

web/src/padelnomics/content/templates/article_detail.html

@@ -4,12 +4,15 @@
 
 {% block head %}
 <meta name="description" content="{{ article.meta_description or '' }}">
-<meta property="og:title" content="{{ article.title }}">
-<meta property="og:description" content="{{ article.meta_description or '' }}">
-<meta property="og:type" content="article">
 {% if article.og_image_url %}
 <meta property="og:image" content="{{ article.og_image_url }}">
 {% endif %}
+{% if article.seo_head %}
+{{ article.seo_head | safe }}
+{% else %}
+<meta property="og:title" content="{{ article.title }}">
+<meta property="og:description" content="{{ article.meta_description or '' }}">
+<meta property="og:type" content="article">
 <script type="application/ld+json">
 {
   "@context": "https://schema.org",
@@ -18,20 +21,15 @@
   "description": {{ (article.meta_description or '') | tojson }},
   {% if article.og_image_url %}"image": {{ article.og_image_url | tojson }},{% endif %}
   "datePublished": "{{ article.published_at[:10] if article.published_at else '' }}",
-  "author": {
+  "author": {"@type": "Organization", "name": "Padelnomics"},
-    "@type": "Organization",
-    "name": "Padelnomics"
-  },
   "publisher": {
     "@type": "Organization",
     "name": "Padelnomics",
-    "logo": {
+    "logo": {"@type": "ImageObject", "url": "{{ url_for('static', filename='images/logo.png', _external=True) }}"}
-      "@type": "ImageObject",
-      "url": "{{ url_for('static', filename='images/logo.png', _external=True) }}"
-    }
   }
 }
 </script>
+{% endif %}
 {% endblock %}
 
 {% block content %}