fix: Windows path handling, light theme default, file viewer in editor, first-user admin logic

Config:
- Fixed SQLite path parsing on Windows (handle drive letters without prepending /)
- Changed default theme from dark to light
- Updated OAuth test credentials (gitea_oauth_client_id/secret)

Auth:
- First real user (excluding default admin with no password) becomes admin
- Changed user count query to exclude users without password_hash

File viewer:
- Removed separate _render_file_viewer() —

app/templates/settings.html

@@ -11,8 +11,8 @@
 
 {% block content %}
 <style>
-.settings-overlay{position:fixed;inset:0;z-index:500;display:flex;background:rgba(0,0,0,.5);backdrop-filter:blur(2px);}
-.settings-panel{display:flex;width:1050px;max-width:98vw;height:85vh;margin:auto;background:var(--bg-primary);border:1px solid var(--border-strong);border-radius:14px;box-shadow:0 16px 48px rgba(0,0,0,.6);overflow:hidden;}
+.settings-overlay{position:fixed;inset:0;z-index:500;display:flex;background:rgba(0,0,0,.4);backdrop-filter:blur(2px);}
+.settings-panel{display:flex;width:1050px;max-width:98vw;height:85vh;margin:auto;background:var(--bg-primary);border:1px solid var(--border-strong);border-radius:14px;box-shadow:var(--shadow-modal);overflow:hidden;}
 .settings-nav{width:200px;min-width:200px;background:var(--bg-sidebar);border-right:1px solid var(--border);padding:8px 0;overflow-y:auto;}
 .settings-nav-header{padding:12px 16px;font-size:13px;font-weight:600;color:var(--text-dim);text-transform:uppercase;letter-spacing:.5px;}
 .settings-nav-item{display:flex;align-items:center;gap:8px;padding:6px 16px;font-size:13px;color:var(--text-secondary);cursor:pointer;transition:background 100ms;border-radius:0;}
@@ -38,7 +38,7 @@
 .avatar-upload-input{display:none;}
 
 /* Avatar color swatches */
-.avatar-color-swatch{width:40px;height:40px;border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:18px;font-weight:700;color:#fff;cursor:pointer;border:2px solid transparent;transition:all 120ms;}
+.avatar-color-swatch{width:40px;height:40px;border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:18px;font-weight:700;color:var(--text-primary);cursor:pointer;border:2px solid transparent;transition:all 120ms;}
 .avatar-color-swatch:hover{transform:scale(1.1);}
 .avatar-color-swatch.selected{border-color:var(--accent);box-shadow:0 0 0 2px rgba(35,131,226,.4);}
 
@@ -54,7 +54,7 @@
 .color-swatch.selected{border-color:var(--text);box-shadow:0 0 0 2px var(--accent);}
 
 /* Admin tables */
-.table-wrap{overflow-x:auto;border-radius:8px;border:1px solid #333;}
+.table-wrap{overflow-x:auto;border-radius:8px;border:1px solid var(--border);}
 .admin-table{width:100%;border-collapse:collapse;font-size:13px;}
 .admin-table th{background:var(--bg-tertiary);color:var(--text-dim);font-weight:500;padding:8px 12px;text-align:left;font-size:11px;text-transform:uppercase;letter-spacing:.5px;white-space:nowrap;}
 .admin-table td{padding:8px 12px;border-top:1px solid var(--border);color:var(--text);}
@@ -63,11 +63,11 @@
 .stat-value{font-size:22px;font-weight:700;color:var(--accent);}
 .stat-label{font-size:11px;color:var(--text-dim);margin-top:2px;text-transform:uppercase;letter-spacing:.5px;}
 .role-badge{display:inline-block;padding:2px 8px;border-radius:10px;font-size:11px;font-weight:500;}
-.role-admin{background:rgba(35,131,226,.2);color:#4DA3F5;}
+.role-admin{background:rgba(35,131,226,.2);color:var(--accent);}
 .role-user{background:rgba(120,119,116,.2);color:var(--text-dim);}
 .status-dot{display:inline-block;width:6px;height:6px;border-radius:50%;margin-right:5px;vertical-align:middle;}
-.status-dot.active{background:#0F7B6C;}
-.status-dot.inactive{background:#E03E3E;}
+.status-dot.active{background:var(--toast-success-bg);}
+.status-dot.inactive{background:var(--danger);}
 
 /* Close button */
 .settings-close{position:absolute;top:12px;right:12px;width:32px;height:32px;background:none;border:none;color:var(--text-dim);font-size:20px;cursor:pointer;border-radius:6px;display:flex;align-items:center;justify-content:center;}
@@ -154,7 +154,7 @@
               <span x-show="!accountSaving">💾 Save changes</span>
               <span x-show="accountSaving">Saving…</span>
             </button>
-            <span x-show="accountMsg" x-text="accountMsg" style="margin-left:12px;font-size:13px;color:#0F7B6C;"></span>
+            <span x-show="accountMsg" x-text="accountMsg" style="margin-left:12px;font-size:13px;color:var(--toast-success-bg);"></span>
           </div>
         </div>
 
@@ -280,7 +280,7 @@
             <h3 style="margin:0 0 8px;">Delete tag</h3>
             <p style="color:var(--text-dim);margin:0 0 16px;">
               Are you sure you want to delete the tag "<strong x-text="deletingTag?.name"></strong>"?
-              <span x-show="deletingTag?.count > 0" style="color:#E03E3E;display:block;margin-top:4px;">
+              <span x-show="deletingTag?.count > 0" style="color:var(--danger);display:block;margin-top:4px;">
                 ⚠️ This tag is used on <span x-text="deletingTag?.count"></span> item(s).
               </span>
             </p>
@@ -324,7 +324,7 @@
               </div>
             </div>
             <div class="setting-control">
-              <span x-show="giteaLinked" style="font-size:12px;color:#0F7B6C;">✅ Active</span>
+              <span x-show="giteaLinked" style="font-size:12px;color:var(--toast-success-bg);">✅ Active</span>
               <button x-show="giteaLinked && authMethod!=='gitea'" class="btn-sm" style="color:var(--danger);" @click="disconnectGitea()">Disconnect</button>
               <a x-show="!giteaLinked" class="btn-sm" href="/auth/login?provider=gitea&mode=link" style="text-decoration:none;color:var(--accent);">🔗 Connect</a>
             </div>
@@ -339,7 +339,7 @@
               </div>
             </div>
             <div class="setting-control">
-              <span x-show="githubLinked" style="font-size:12px;color:#0F7B6C;">✅ Active</span>
+              <span x-show="githubLinked" style="font-size:12px;color:var(--toast-success-bg);">✅ Active</span>
               <button x-show="githubLinked && authMethod!=='github'" class="btn-sm" style="color:var(--danger);" @click="disconnectGithub()">Disconnect</button>
               <a x-show="!githubLinked" class="btn-sm" href="/auth/login?provider=github&mode=link" style="text-decoration:none;color:var(--accent);">🔗 Connect</a>
             </div>
@@ -522,7 +522,7 @@ document.addEventListener('alpine:init', function() {
       giteaLinked: false,
       githubLinked: false,
       // Theme
-      theme: localStorage.getItem('fd_theme') || 'dark',
+      theme: localStorage.getItem('fd_theme') || 'light',
       // Account form
       accountForm: {login:'{{ user.login or "" }}', full_name:'{{ user.full_name or "" }}', email:'{{ user.email or "" }}', password:''},
       accountSaving: false,
@@ -739,26 +739,6 @@ document.addEventListener('alpine:init', function() {
       applyTheme() {
         localStorage.setItem('fd_theme', this.theme);
         document.documentElement.setAttribute('data-theme', this.theme);
-        if (this.theme === 'light') {
-          document.documentElement.style.setProperty('--bg-primary', '#FFFFFF');
-          document.documentElement.style.setProperty('--bg-secondary', '#F7F6F3');
-          document.documentElement.style.setProperty('--bg-tertiary', '#EDECE9');
-          document.documentElement.style.setProperty('--text', '#37352F');
-          document.documentElement.style.setProperty('--text-secondary', '#6B6966');
-          document.documentElement.style.setProperty('--text-dim', '#9B9A97');
-          document.documentElement.style.setProperty('--border', '#E0DFDC');
-          document.documentElement.style.setProperty('--border-strong', '#CCCBC8');
-        } else {
-          document.documentElement.style.removeProperty('--bg-primary');
-          document.documentElement.style.removeProperty('--bg-secondary');
-          document.documentElement.style.removeProperty('--bg-tertiary');
-          document.documentElement.style.removeProperty('--text');
-          document.documentElement.style.removeProperty('--text-secondary');
-          document.documentElement.style.removeProperty('--text-dim');
-          document.documentElement.style.removeProperty('--border');
-          document.documentElement.style.removeProperty('--border-strong');
-          document.documentElement.setAttribute('data-theme', 'dark');
-        }
       },
 
       saveDefaultView() {