gitcitadel branding: logos, favicons, og-image + CSS adjustments

- assets/laeserin_logo.png → GitCitadel_Graphic_Landscape.png (header banner)
- assets/theme/local/og-image.jpg → same landscape logo (OG / share preview)
- assets/theme/local/icons/ → GitCitadel_PFP.png resized to all required sizes:
    favicon.ico (32×32), favicon-96x96.png, apple-touch-icon.png (180×180),
    web-app-manifest-192x192.png, web-app-manifest-512x512.png
- app.css: header__logo-banner → object-fit: contain + center (landscape logo,
    not portrait crop); card-header--no-cover img same change
- .gitignore: track all theme/local assets in this branch

Co-authored-by: Cursor <cursoragent@cursor.com>

assets/styles/app.css

@@ -736,10 +736,9 @@ svg.icon {
     text-underline-offset: 2px;
 }
 
-/* Fallback hero: portrait painting at low opacity with a diagonal stripe overlay.
+/* Fallback hero: landscape logo at low opacity with a diagonal stripe overlay.
    Applied to any card container (.card-header, .featured-tile__media, etc.) when
-   the article has no cover image. The painting is cropped to the face — same
-   object-position as .header__logo-banner. */
+   the article has no cover image. Logo is shown in full (contain + center). */
 .card-header--no-cover {
     position: relative;
     overflow: hidden;
@@ -748,8 +747,8 @@ svg.icon {
 
 .card-header--no-cover img {
     opacity: 0.18;
-    object-fit: cover;
-    object-position: 50% 14%;
+    object-fit: contain;
+    object-position: center;
 }
 
 .card-header--no-cover::after {
@@ -1148,19 +1147,15 @@ svg.icon {
     }
 }
 
-/* Horizontal banner logo: portrait painting cropped to a wide strip that shows the
-   subject's face/upper body. object-position 50% 14% targets the face at the top
-   of the portrait; adjust the Y value if the crop drifts on a different painting. */
+/* Horizontal banner logo: landscape logo image shown in full (contain + center). */
 .header__logo-banner {
     display: block;
     flex-shrink: 0;
-    /* Width drives the banner proportions; height clips into the portrait. */
     width: 140px;
     height: 48px;
-    object-fit: cover;
-    object-position: 50% 14%;
+    object-fit: contain;
+    object-position: center;
     border-radius: 5px;
-    box-shadow: 0 0 0 1px var(--color-border);
     /* Prevent global img { height: auto } from overriding the fixed height. */
     max-width: none;
 }

assets/theme/local/.gitignore

@@ -1,2 +1 @@
-icons
-# theme.css and theme-dark.css are tracked in this branch (gitcitadel brand assets)
+# All theme/local assets are tracked in this branch (gitcitadel brand assets)