Fix icon and avatar rendering: remove SVG viewport rects + inline avatar styles

- Removed the <rect x='0' y='0' width='24' height='24' fill='none'> viewport
  markers from each social-share SVG. With 'fill=none' the rect was
  still visible if any inherited stroke wasn't suppressed (which turned
  out to be unreliable across themes/CSS specificity).
- Removed redundant width='24' height='24' attributes from each SVG so
  the CSS .project-social-sharing svg { width:20px; height:20px } can
  size them unambiguously.
- Inlined avatar <img> styles (width:50px; height:50px; border-radius:50%;
  object-fit:cover; flex-shrink:0; display:block) so the avatar is
  guaranteed to render as a 50x50 circle regardless of theme CSS.
- Switched .project-owner-avatar to inline-flex so the span shrinks to
  the image's natural size within the flex parent.

templates/single-projects.php

@@ -144,7 +144,7 @@ if ( $last_updated ) {
                 <a href="<?php echo esc_url( $browse_url ); ?>">
                 <div class="project-owner">
                     <span class="project-owner-avatar">
-                        <img src="<?php echo esc_url( $owner_avatar ); ?>" alt="<?php esc_attr_e( $owner_name ); ?>" class="owner-avatar" />
+                        <img src="<?php echo esc_url( $owner_avatar ); ?>" alt="<?php esc_attr_e( $owner_name ); ?>" class="owner-avatar" style="display:block;width:50px;height:50px;border-radius:50%;object-fit:cover;flex-shrink:0;margin:0;" />
                     </span>
                     <span class="project-owner-name">
                         <strong>