feat: Implement Electron window state persistence, update checking with splash screen and banner, and external link metadata fetching.

Frontend/Electron/main.cjs

@@ -346,6 +346,44 @@ app.whenReady().then(async () => {
         }
     });
 
+    // Flatpak update check
+    ipcMain.handle('check-flatpak-update', async () => {
+        const isFlatpak = fs.existsSync('/.flatpak-info') || !!process.env.FLATPAK_ID;
+        if (!isFlatpak) return { isFlatpak: false };
+
+        try {
+            const yaml = await httpGet('https://gitea.moyettes.com/Moyettes/DiscordClone/releases/download/latest/latest-linux.yml');
+            if (!yaml) return { isFlatpak: true, updateAvailable: false };
+
+            const versionMatch = yaml.match(/^version:\s*(.+)$/m);
+            if (!versionMatch) return { isFlatpak: true, updateAvailable: false };
+
+            const latestVersion = versionMatch[1].trim();
+            const currentVersion = app.getVersion();
+
+            // Semver comparison: determine if update exists and its severity
+            const latest = latestVersion.split('.').map(Number);
+            const current = currentVersion.split('.').map(Number);
+            let updateAvailable = false;
+            let updateType = 'patch'; // 'major', 'minor', or 'patch'
+            for (let i = 0; i < Math.max(latest.length, current.length); i++) {
+                const l = latest[i] || 0;
+                const c = current[i] || 0;
+                if (l > c) {
+                    updateAvailable = true;
+                    updateType = i === 0 ? 'major' : i === 1 ? 'minor' : 'patch';
+                    break;
+                }
+                if (l < c) break;
+            }
+
+            return { isFlatpak: true, updateAvailable, updateType, latestVersion, currentVersion };
+        } catch (err) {
+            console.error('Flatpak update check error:', err.message);
+            return { isFlatpak: true, updateAvailable: false };
+        }
+    });
+
     ipcMain.handle('open-external', async (event, url) => {
         await shell.openExternal(url);
     });