feat(auth): add user identity verification system with new screens

Add comprehensive identity verification flow including:
- New verification guide screen at /verification-guide for selecting identity type
- New verification form screen at /verification-form for submitting verification documents
- Verification settings screen at /profile/verification for managing verification status
- Move terms and privacy policy to root-level routes (/terms, /privacy)
- Update login to require active terms agreement checkbox
- Database: add in-memory fallback when OPFS is unavailable on web

BREAKING CHANGE: Terms and privacy policy routes moved from /profile/terms and /profile/privacy to /terms and /privacy

src/database/core/DatabaseConfig.ts

@@ -9,6 +9,6 @@ export const DB_CONFIG = {
   DB_NAME_PREFIX: 'carrot_bbs_',
 } as const;
 
-export const getDbName = (userId: string | null): string => {
+export function getDbName(userId: string | null): string {
   return userId ? `${DB_CONFIG.DB_NAME_PREFIX}${userId}.db` : DB_CONFIG.DEFAULT_DB_NAME;
-};
+}

src/database/core/DatabaseManager.ts

@@ -109,25 +109,31 @@ class DatabaseManager {
     const isWeb = typeof window !== 'undefined';
 
     return LockManager.withWebLock(`${DB_CONFIG.LOCK_PREFIX}${dbName}`, async () => {
+      let lastError: unknown;
       for (let attempt = 0; attempt <= DB_CONFIG.MAX_RETRIES; attempt++) {
         try {
           const database = await SQLite.openDatabaseAsync(dbName);
           console.log(`[DatabaseManager] 成功打开数据库 (尝试 ${attempt + 1}/${DB_CONFIG.MAX_RETRIES + 1})`);
           return database;
         } catch (error) {
+          lastError = error;
           const msg = String(error);
           console.error(`[DatabaseManager] 打开失败 (尝试 ${attempt + 1}/${DB_CONFIG.MAX_RETRIES + 1}):`, msg);
 
+          if (isWeb && msg.includes('cannot create file')) {
+            console.log('[DatabaseManager] OPFS 不可用，回退到内存数据库');
+            const memoryDb = await SQLite.openDatabaseAsync(':memory:');
+            return memoryDb;
+          }
+
           if (attempt < DB_CONFIG.MAX_RETRIES) {
             const delay = isWeb ? DB_CONFIG.WEB_RETRY_DELAY_BASE * (attempt + 1) : DB_CONFIG.NATIVE_RETRY_DELAY;
             console.warn(`[DatabaseManager] ${delay}ms 后重试...`);
             await new Promise(r => setTimeout(r, delay));
-          } else {
-            throw error;
           }
         }
       }
-      throw new Error('打开数据库失败');
+      throw lastError;
     });
   }