fix(duckdb): support multiple schemas beyond default "main"

DuckDB was not recognized as a schema-aware database, so only the
default "main" schema was shown in the object tree and schema selector.
Added DuckDB to schema-aware type lists, implemented schema listing via
information_schema.schemata, and replaced hardcoded table_schema = 'main'
with parameterized queries.

apps/desktop/src/lib/databaseCapabilitySets.ts

@@ -25,6 +25,7 @@ export const SCHEMA_AWARE_TYPES = new Set<DatabaseType>([
   "trino",
   "db2",
   "tdengine",
+  "duckdb",
 ]);
 
 export const SQL_FILE_UNSUPPORTED_TYPES = new Set<DatabaseType>(["redis", "mongodb", "elasticsearch"]);
@@ -201,6 +202,7 @@ export const TREE_SCHEMA_TYPES = new Set<DatabaseType>([
   "trino",
   "h2",
   "tdengine",
+  "duckdb",
 ]);
 
 export const PG_LIKE_STRUCTURE_TYPES = new Set<DatabaseType>(["postgres", "redshift", "gaussdb", "opengauss"]);