feat: add GaussDB ODBC support and flatten connection list

- Add GaussDB/openGauss support via ODBC (resolves #106)
- Use pg_catalog queries instead of information_schema for compatibility
- Share ODBC environment across drivers with auto ODBCSYSINI detection
- Fix ODBC error message false positive on "Driver" keyword match
- Merge connection dialog categories into a single flat list
- Remove duplicate DDL button from data grid footer

src/i18n/locales/en.ts

@@ -113,6 +113,8 @@ export default {
     sshExposeLan: "Expose tunnel to LAN",
     dmCompatHint: "Requires DM8 ODBC driver installed on your system.",
     dmDownload: "Download from Dameng",
+    gaussdbOdbcHint: "Requires GaussDB ODBC driver installed on your system.",
+    gaussdbDownload: "Download from Huawei Cloud",
     mongoLegacyHint:
       "For older MongoDB servers, enter authSource=admin&authMechanism=SCRAM-SHA-1 here; add directConnection=true only when needed for direct standalone connections.",
     compatible: "Compatible",

src/i18n/locales/zh-CN.ts

@@ -112,6 +112,8 @@ export default {
     sshExposeLan: "允许局域网访问隧道",
     dmCompatHint: "需要在系统上安装达梦 DM8 ODBC 驱动程序。",
     dmDownload: "前往达梦官网下载",
+    gaussdbOdbcHint: "需要在系统上安装 GaussDB ODBC 驱动程序。",
+    gaussdbDownload: "前往华为云下载",
     mongoLegacyHint:
       "连接旧版 MongoDB 时，可在此填写 authSource=admin&authMechanism=SCRAM-SHA-1；直连单节点时可按需追加 directConnection=true。",
     compatible: "兼容",