Add favicon and update navigation icons across documentation

- Added a favicon link to all tour pages in the Japanese documentation.
- Updated navigation links to include SVG icons for Home and GitHub.
- Changed language button to include an SVG icon for better visual representation.
- Improved theme toggle button to use SVG icons for light and dark modes.
- Refactored the documentation build commands in the justfile for clarity and consistency.

docs-gen/defaults/static/css/main.css

@@ -86,14 +86,22 @@ a:hover {
 }
 
 .header-nav a {
+  display: flex;
+  align-items: center;
+  gap: 4px;
   color: var(--header-nav-link);
   font-size: 0.9rem;
 }
 
+.header-nav a svg {
+  flex-shrink: 0;
+  opacity: 0.85;
+}
+
 .header-tools {
   display: flex;
   align-items: center;
-  gap: 8px;
+  gap: 2px;
 }
 
 .lang-selector {
@@ -101,17 +109,21 @@ a:hover {
 }
 
 .lang-btn {
+  display: flex;
+  align-items: center;
+  gap: 5px;
   background: none;
-  border: 1px solid var(--text-muted);
+  border: none;
   color: var(--text);
-  padding: 4px 10px;
+  padding: 4px 6px;
   border-radius: 4px;
   cursor: pointer;
   font-size: 0.85rem;
+  opacity: 0.8;
 }
 
 .lang-btn:hover {
-  border-color: var(--text);
+  opacity: 1;
 }
 
 .lang-popup {
@@ -423,16 +435,18 @@ a:hover {
 
 /* Theme toggle */
 .theme-toggle {
+  display: flex;
+  align-items: center;
+  justify-content: center;
   background: none;
-  border: 1px solid var(--text-muted);
+  border: none;
   color: var(--text);
-  padding: 4px 8px;
+  padding: 5px 6px;
   border-radius: 4px;
   cursor: pointer;
-  font-size: 1rem;
-  line-height: 1;
+  opacity: 0.8;
 }
 
 .theme-toggle:hover {
-  border-color: var(--text);
+  opacity: 1;
 }

docs-gen/defaults/static/favicon.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="size-6">
+  <path stroke-linecap="round" stroke-linejoin="round" d="M9.594 3.94c.09-.542.56-.94 1.11-.94h2.593c.55 0 1.02.398 1.11.94l.213 1.281c.063.374.313.686.645.87.074.04.147.083.22.127.325.196.72.257 1.075.124l1.217-.456a1.125 1.125 0 0 1 1.37.49l1.296 2.247a1.125 1.125 0 0 1-.26 1.431l-1.003.827c-.293.241-.438.613-.43.992a7.723 7.723 0 0 1 0 .255c-.008.378.137.75.43.991l1.004.827c.424.35.534.955.26 1.43l-1.298 2.247a1.125 1.125 0 0 1-1.369.491l-1.217-.456c-.355-.133-.75-.072-1.076.124a6.47 6.47 0 0 1-.22.128c-.331.183-.581.495-.644.869l-.213 1.281c-.09.543-.56.94-1.11.94h-2.594c-.55 0-1.019-.398-1.11-.94l-.213-1.281c-.062-.374-.312-.686-.644-.87a6.52 6.52 0 0 1-.22-.127c-.325-.196-.72-.257-1.076-.124l-1.217.456a1.125 1.125 0 0 1-1.369-.49l-1.297-2.247a1.125 1.125 0 0 1 .26-1.431l1.004-.827c.292-.24.437-.613.43-.991a6.932 6.932 0 0 1 0-.255c.007-.38-.138-.751-.43-.992l-1.004-.827a1.125 1.125 0 0 1-.26-1.43l1.297-2.247a1.125 1.125 0 0 1 1.37-.491l1.216.456c.356.133.751.072 1.076-.124.072-.044.146-.086.22-.128.332-.183.582-.495.644-.869l.214-1.28Z" />
+  <path stroke-linecap="round" stroke-linejoin="round" d="M15 12a3 3 0 1 1-6 0 3 3 0 0 1 6 0Z" />
+</svg>

docs-gen/defaults/static/js/main.js

@@ -33,6 +33,10 @@
   var btn = document.querySelector('.theme-toggle');
   if (!btn) return;
 
+  // Feather Icons: sun (light mode) and moon (dark mode)
+  var sunSVG = '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="5"/><line x1="12" y1="1" x2="12" y2="3"/><line x1="12" y1="21" x2="12" y2="23"/><line x1="4.22" y1="4.22" x2="5.64" y2="5.64"/><line x1="18.36" y1="18.36" x2="19.78" y2="19.78"/><line x1="1" y1="12" x2="3" y2="12"/><line x1="21" y1="12" x2="23" y2="12"/><line x1="4.22" y1="19.78" x2="5.64" y2="18.36"/><line x1="18.36" y1="5.64" x2="19.78" y2="4.22"/></svg>';
+  var moonSVG = '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z"/></svg>';
+
   function getTheme() {
     var stored = localStorage.getItem('preferred-theme');
     if (stored) return stored;
@@ -45,7 +49,7 @@
     } else {
       document.documentElement.removeAttribute('data-theme');
     }
-    btn.textContent = theme === 'light' ? '\u2600\uFE0F' : '\uD83C\uDF19';
+    btn.innerHTML = theme === 'light' ? sunSVG : moonSVG;
   }
 
   applyTheme(getTheme());