feat(setup): redirect to /loading instead of / after setup flow

- loading.html: check for unresolved folders before redirecting, go to /login if none
- unresolved.html: redirect to /loading instead of / after skip/timeout
- add docs/NAVIGATION.md navigation flow documentation

src/server/web/templates/loading.html

@@ -475,9 +475,26 @@
         }
 
         async function checkUnresolvedAndProceed() {
-            // Always redirect to /setup/unresolved after initialization
-            // so users can manually enter unresolved animes
-            window.location.href = '/setup/unresolved';
+            // Fetch unresolved folders and only redirect if there are any
+            // Otherwise go directly to login
+            try {
+                const token = localStorage.getItem('auth_token');
+                const res = await fetch('/api/setup/unresolved', {
+                    headers: { 'Authorization': `Bearer ${token}` }
+                });
+                if (res.ok) {
+                    const folders = await res.json();
+                    if (folders && folders.length > 0) {
+                        // Has unresolved folders - go to resolution page
+                        window.location.href = '/setup/unresolved';
+                        return;
+                    }
+                }
+            } catch (err) {
+                console.error('Failed to check unresolved folders:', err);
+            }
+            // No unresolved folders or error - go to login
+            window.location.href = '/login';
         }
 
         function showError(message) {

src/server/web/templates/unresolved.html

@@ -552,7 +552,7 @@
                 listEl.style.display = 'none';
                 emptyEl.style.display = 'block';
                 document.getElementById('skip-link').style.display = 'block';
-                setTimeout(() => { window.location.href = '/'; }, 2000);
+                setTimeout(() => { window.location.href = '/loading'; }, 2000);
             } else {
                 listEl.style.display = 'flex';
                 emptyEl.style.display = 'none';
@@ -690,7 +690,7 @@
                 emptyEl.style.display = 'block';
                 skipLink.style.display = 'block';
                 showToast('All series configured!', 'success');
-                setTimeout(() => { window.location.href = '/'; }, 2000);
+                setTimeout(() => { window.location.href = '/loading'; }, 2000);
             }
         }