fix: make postgresql actually usable (4 critical bugs)

- CORS whitelist only allowed origin localhost:5173; browsers send Origin
  on same-origin POST too, so every deployment on any other port/origin
  got empty 403 on ALL POST/PUT/DELETE (curl tests masked it) - now
  echoes any origin (bearer-token auth, no cookie CSRF surface)
- connection_tester pg DSN had a literal *** password placeholder - pg
  connection test and query path could never authenticate
- instance detail endpoints (databases/tables/db-schema/table-detail)
  ran MySQL SHOW statements against pg - added pg branches
  (pg_database/pg_class/information_schema/pg_indexes, search_path
  semantics, PRI detection); schema filter uses non-system schemas
- frontend normalizeDbType missed the literal 'postgresql' value so pg
  instances were treated as mysql (backtick quoting, no column hints);
  genSql no longer emits db.table prefix for pg (schema semantics)
- also: query page footer warnings condensed to a single line per db type

verified live: mysql table tree/context menu/preview-execute; pg table
tree/columns/PK, double-click preview with masking working (email/phone
masked), query history persisted

backend/internal/handler/instance_detail.go

@@ -45,6 +45,26 @@ func DetailListDatabases(c *gin.Context) {
 	}
 	defer db.Close()
 
+	if instance.DBType == "postgresql" || instance.DBType == "postgres" || instance.DBType == "pg" {
+		pgRows, err := db.Query("SELECT datname FROM pg_database WHERE NOT datistemplate AND datallowconn ORDER BY 1")
+		if err != nil {
+			resp.InternalErr(c, err)
+			return
+		}
+		defer pgRows.Close()
+		var databases []string
+		for pgRows.Next() {
+			var name string
+			pgRows.Scan(&name)
+			databases = append(databases, name)
+		}
+		if databases == nil {
+			databases = []string{}
+		}
+		c.JSON(http.StatusOK, databases)
+		return
+	}
+
 	rows, err := db.Query("SHOW DATABASES")
 	if err != nil {
 		resp.InternalErr(c, err)
@@ -99,6 +119,33 @@ func DetailListTables(c *gin.Context) {
 	}
 	defer db.Close()
 
+	if instance.DBType == "postgresql" || instance.DBType == "postgres" || instance.DBType == "pg" {
+		pgRows, err := db.Query(`SELECT c.relname AS name, c.reltuples::bigint AS rows,
+			pg_total_relation_size(c.oid) AS data_length
+			FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace
+			WHERE n.nspname NOT IN ('pg_catalog', 'information_schema') AND c.relkind = 'r'
+			ORDER BY c.relname`)
+		if err != nil {
+			resp.InternalErr(c, err)
+			return
+		}
+		defer pgRows.Close()
+		var tables []map[string]interface{}
+		for pgRows.Next() {
+			var name string
+			var rowCount, dataLen int64
+			pgRows.Scan(&name, &rowCount, &dataLen)
+			tables = append(tables, map[string]interface{}{
+				"name": name, "rows": rowCount, "data_length": dataLen, "engine": "postgres",
+			})
+		}
+		if tables == nil {
+			tables = []map[string]interface{}{}
+		}
+		c.JSON(http.StatusOK, tables)
+		return
+	}
+
 	rows, err := db.Query("SHOW TABLE STATUS")
 	if err != nil {
 		resp.InternalErr(c, err)
@@ -166,6 +213,27 @@ func DetailDbSchema(c *gin.Context) {
 	}
 	defer db.Close()
 
+	schema := make(map[string][]string)
+
+	if instance.DBType == "postgresql" || instance.DBType == "postgres" || instance.DBType == "pg" {
+		// PG:一次查询拿全部 库内表.列(information_schema)
+		colRows, err := db.Query(`SELECT table_name, column_name FROM information_schema.columns
+			WHERE table_schema NOT IN ('pg_catalog', 'information_schema')
+			ORDER BY table_name, ordinal_position`)
+		if err != nil {
+			resp.InternalErr(c, err)
+			return
+		}
+		defer colRows.Close()
+		for colRows.Next() {
+			var tableName, columnName string
+			colRows.Scan(&tableName, &columnName)
+			schema[tableName] = append(schema[tableName], columnName)
+		}
+		c.JSON(http.StatusOK, schema)
+		return
+	}
+
 	// Get all tables and their columns
 	tableRows, err := db.Query("SHOW TABLES")
 	if err != nil {
@@ -174,7 +242,6 @@ func DetailDbSchema(c *gin.Context) {
 	}
 	defer tableRows.Close()
 
-	schema := make(map[string][]string)
 	for tableRows.Next() {
 		var tableName string
 		tableRows.Scan(&tableName)
@@ -229,6 +296,79 @@ func DetailTableDetail(c *gin.Context) {
 	}
 	defer db.Close()
 
+	if instance.DBType == "postgresql" || instance.DBType == "postgres" || instance.DBType == "pg" {
+		// PG:information_schema 拼列 + pg_indexes 拿索引(无 SHOW CREATE,DDL 以列清单形式给出)
+		colRows, err := db.Query(`SELECT column_name, data_type, is_nullable,
+			COALESCE(column_default, ''), character_maximum_length
+			FROM information_schema.columns
+			WHERE table_schema NOT IN ('pg_catalog', 'information_schema') AND table_name = $1
+			ORDER BY ordinal_position`, tableName)
+		if err != nil {
+			resp.InternalErr(c, err)
+			return
+		}
+		defer colRows.Close()
+		var columns []map[string]interface{}
+		var ddlLines []string
+		for colRows.Next() {
+			var name, dataType, nullable, def string
+			var maxLen interface{}
+			colRows.Scan(&name, &dataType, &nullable, &def, &maxLen)
+			nullStr := "YES"
+			if nullable != "YES" {
+				nullStr = "NO"
+			}
+			key := ""
+			pkRows, _ := db.Query(`SELECT a.attname FROM pg_index i
+				JOIN pg_attribute a ON a.attrelid = i.indrelid AND a.attnum = ANY(i.indkey)
+				WHERE i.indrelid = to_regclass($1) AND i.indisprimary`, tableName)
+			if pkRows != nil {
+				for pkRows.Next() {
+					var pk string
+					pkRows.Scan(&pk)
+					if pk == name {
+						key = "PRI"
+					}
+				}
+				pkRows.Close()
+			}
+			columns = append(columns, map[string]interface{}{
+				"Field": name, "Type": dataType, "Null": nullStr, "Key": key, "Default": def, "Extra": "",
+			})
+			ddlLines = append(ddlLines, "  "+name+" "+dataType+(func() string {
+				if nullStr == "NO" {
+					return " NOT NULL"
+				}
+				return ""
+			})())
+		}
+		ddl := "CREATE TABLE " + tableName + " (\n" + strings.Join(ddlLines, ",\n") + "\n);"
+
+		idxRows, err := db.Query(`SELECT indexname, indexdef FROM pg_indexes
+			WHERE schemaname NOT IN ('pg_catalog', 'information_schema') AND tablename = $1
+			ORDER BY indexname`, tableName)
+		var indexes []map[string]interface{}
+		if err == nil {
+			defer idxRows.Close()
+			for idxRows.Next() {
+				var idxName, idxDef string
+				idxRows.Scan(&idxName, &idxDef)
+				nonUnique := !strings.Contains(idxDef, " UNIQUE INDEX ")
+				indexes = append(indexes, map[string]interface{}{
+					"Key_name": idxName, "Column_name": strings.Trim(idxDef[strings.LastIndex(idxDef, "(")+1:], ")"), "Non_unique": nonUnique, "Index_type": "btree",
+				})
+			}
+		}
+		if indexes == nil {
+			indexes = []map[string]interface{}{}
+		}
+		if columns == nil {
+			columns = []map[string]interface{}{}
+		}
+		c.JSON(http.StatusOK, gin.H{"ddl": ddl, "columns": columns, "indexes": indexes})
+		return
+	}
+
 	// Get DDL
 	var ddl string
 	db.QueryRow("SHOW CREATE TABLE `"+tableName+"`").Scan(&tableName, &ddl)