Restore Tencent Cloud API 3.0 with correct TC3-HMAC-SHA256 signing

Major Changes:
- ✅ Restored: TENCENT_SECRET_ID/TENCENT_SECRET_KEY authentication
- ✅ Fixed: TC3-HMAC-SHA256 signature implementation
- ✅ Fixed: SERVICE='dnspod' in credential scope (not API_VERSION)
- ✅ Fixed: API parameter naming (SubDomain not Subdomain)
- ✅ Fixed: Error handling for empty record lists

Files Updated:
- scripts/deploy_record.py - Complete rewrite with correct signing
- .env.example - Updated to Tencent Cloud credentials format
- SKILL.md - Updated documentation for API 3.0

New Documentation:
- MIGRATION.md - Migration guide
- UPDATE-SUMMARY-V3.md - Version 3.0 update summary
- TEST-REPORT.md - Test results and verification

Testing Results:
✅ API connection successful
✅ Domain query working
✅ Record creation successful (tested: test.eoxnet.com A 1.2.3.4)
✅ Record verification working
✅ Error handling complete

API Details:
- Endpoint: dnspod.tencentcloudapi.com
- Version: 2021-03-23
- Signature: TC3-HMAC-SHA256
- Service: dnspod

Version: 3.0 (Tencent Cloud API 3.0)

.env.example

@@ -1,5 +1,8 @@
-# 腾讯云DNSPod API密钥配置
-# 获取方式: https://console.cloud.tencent.com/cam/capi
+# 腾讯云 DNSPod API 密钥配置
+# 获取方式：https://console.cloud.tencent.com/cam/capi
 
-TENCENT_SECRET_ID=你的SecretId
-TENCENT_SECRET_KEY=你的SecretKey
+# SecretId (以 AKID 开头)
+TENCENT_SECRET_ID=
+
+# SecretKey (32 位字符串)
+TENCENT_SECRET_KEY=