feat: add database, role & privilege management

Add Admin sidebar tab with database/role management panels, role manager
workspace tab, and privilege dialogs. Backend provides 10 new Tauri
commands for CRUD on databases, roles, and privileges with read-only
mode enforcement. Context menus on schema tree nodes allow dropping
databases and viewing/granting table privileges.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/tauri.ts

@@ -8,6 +8,14 @@ import type {
   ConstraintInfo,
   IndexInfo,
   HistoryEntry,
+  DatabaseInfo,
+  CreateDatabaseParams,
+  RoleInfo,
+  CreateRoleParams,
+  AlterRoleParams,
+  TablePrivilege,
+  GrantRevokeParams,
+  RoleMembershipParams,
 } from "@/types";
 
 // Connections
@@ -162,3 +170,34 @@ export const exportJson = (
   columns: string[],
   rows: unknown[][]
 ) => invoke<void>("export_json", { path, columns, rows });
+
+// Management
+export const getDatabaseInfo = (connectionId: string) =>
+  invoke<DatabaseInfo[]>("get_database_info", { connectionId });
+
+export const createDatabase = (connectionId: string, params: CreateDatabaseParams) =>
+  invoke<void>("create_database", { connectionId, params });
+
+export const dropDatabase = (connectionId: string, name: string) =>
+  invoke<void>("drop_database", { connectionId, name });
+
+export const listRoles = (connectionId: string) =>
+  invoke<RoleInfo[]>("list_roles", { connectionId });
+
+export const createRole = (connectionId: string, params: CreateRoleParams) =>
+  invoke<void>("create_role", { connectionId, params });
+
+export const alterRole = (connectionId: string, params: AlterRoleParams) =>
+  invoke<void>("alter_role", { connectionId, params });
+
+export const dropRole = (connectionId: string, name: string) =>
+  invoke<void>("drop_role", { connectionId, name });
+
+export const getTablePrivileges = (connectionId: string, schema: string, table: string) =>
+  invoke<TablePrivilege[]>("get_table_privileges", { connectionId, schema, table });
+
+export const grantRevoke = (connectionId: string, params: GrantRevokeParams) =>
+  invoke<void>("grant_revoke", { connectionId, params });
+
+export const manageRoleMembership = (connectionId: string, params: RoleMembershipParams) =>
+  invoke<void>("manage_role_membership", { connectionId, params });