Add dark mode support for tables and data pages

- Add CSS overrides for MaterialTable in dark mode
- Update page containers with dark:bg-zinc-950
- Update sidebars with dark mode (MetersSidebar, ConcentratorsSidebar)
- Update tables in AuditoriaPage, UsersPage, RolesPage
- Update ConsumptionPage with dark gradient background
- Update search inputs, select elements, and modals
- Add dark borders for card separation

Affected pages:
- MeterPage, ConcentratorsPage, ProjectsPage
- UsersPage, RolesPage, AuditoriaPage
- ConsumptionPage

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/pages/projects/ProjectsPage.tsx

@@ -159,7 +159,7 @@ export default function ProjectsPage() {
   );
 
   return (
-    <div className="flex gap-6 p-6 w-full bg-gray-100">
+    <div className="flex gap-6 p-6 w-full bg-gray-100 dark:bg-zinc-950">
       <div className="flex-1 flex flex-col gap-6">
         {/* HEADER */}
         <div
@@ -214,7 +214,7 @@ export default function ProjectsPage() {
 
         {/* SEARCH */}
         <input
-          className="bg-white rounded-lg shadow px-4 py-2 text-sm"
+          className="bg-white dark:bg-zinc-900 dark:border dark:border-zinc-800 dark:text-zinc-100 rounded-lg shadow px-4 py-2 text-sm dark:placeholder-zinc-500"
           placeholder="Buscar proyecto..."
           value={search}
           onChange={(e) => setSearch(e.target.value)}